Refactor variable and function names for improved clarity in msg.go

The change updates various variable and function names in msg.go to make the code more intuitive. Updated names better capture what they represent or do, improving code readability and maintainability. This refactor does not impact functionality or logic of the code.

msg.go

@@ -126,8 +126,8 @@ const SendmailPath = "/usr/sbin/sendmail"
 type MsgOption func(*Msg)
 
 // NewMsg returns a new Msg pointer
-func NewMsg(o ...MsgOption) *Msg {
-	m := &Msg{
+func NewMsg(opts ...MsgOption) *Msg {
+	msg := &Msg{
 		addrHeader:    make(map[AddrHeader][]*mail.Address),
 		charset:       CharsetUTF8,
 		encoding:      EncodingQP,
@@ -137,17 +137,17 @@ func NewMsg(o ...MsgOption) *Msg {
 	}
 
 	// Override defaults with optionally provided MsgOption functions
-	for _, co := range o {
-		if co == nil {
+	for _, option := range opts {
+		if option == nil {
 			continue
 		}
-		co(m)
+		option(msg)
 	}
 
 	// Set the matcing mime.WordEncoder for the Msg
-	m.setEncoder()
+	msg.setEncoder()
 
-	return m
+	return msg
 }
 
 // WithCharset overrides the default message charset
@@ -186,9 +186,9 @@ func WithMiddleware(mw Middleware) MsgOption {
 }
 
 // WithPGPType overrides the default PGPType of the message
-func WithPGPType(t PGPType) MsgOption {
+func WithPGPType(pt PGPType) MsgOption {
 	return func(m *Msg) {
-		m.pgptype = t
+		m.pgptype = pt
 	}
 }
 
@@ -232,20 +232,20 @@ func (m *Msg) Charset() string {
 // For adding address headers like "To:" or "From", see SetAddrHeader
 //
 // Deprecated: This method only exists for compatibility reason. Please use SetGenHeader instead
-func (m *Msg) SetHeader(h Header, v ...string) {
-	m.SetGenHeader(h, v...)
+func (m *Msg) SetHeader(header Header, values ...string) {
+	m.SetGenHeader(header, values...)
 }
 
 // SetGenHeader sets a generic header field of the Msg
 // For adding address headers like "To:" or "From", see SetAddrHeader
-func (m *Msg) SetGenHeader(h Header, v ...string) {
+func (m *Msg) SetGenHeader(header Header, values ...string) {
 	if m.genHeader == nil {
 		m.genHeader = make(map[Header][]string)
 	}
-	for i, hv := range v {
-		v[i] = m.encodeString(hv)
+	for i, val := range values {
+		values[i] = m.encodeString(val)
 	}
-	m.genHeader[h] = v
+	m.genHeader[header] = values
 }
 
 // SetHeaderPreformatted sets a generic header field of the Msg which content is
@@ -253,8 +253,8 @@ func (m *Msg) SetGenHeader(h Header, v ...string) {
 //
 // Deprecated: This method only exists for compatibility reason. Please use
 // SetGenHeaderPreformatted instead
-func (m *Msg) SetHeaderPreformatted(h Header, v string) {
-	m.SetGenHeaderPreformatted(h, v)
+func (m *Msg) SetHeaderPreformatted(header Header, value string) {
+	m.SetGenHeaderPreformatted(header, value)
 }
 
 // SetGenHeaderPreformatted sets a generic header field of the Msg which content is
@@ -268,206 +268,207 @@ func (m *Msg) SetHeaderPreformatted(h Header, v string) {
 // user is respondible for the formating of the message header, go-mail cannot
 // guarantee the fully compliance with the RFC 2822. It is recommended to use
 // SetGenHeader instead.
-func (m *Msg) SetGenHeaderPreformatted(h Header, v string) {
+func (m *Msg) SetGenHeaderPreformatted(header Header, value string) {
 	if m.preformHeader == nil {
 		m.preformHeader = make(map[Header]string)
 	}
-	m.preformHeader[h] = v
+	m.preformHeader[header] = value
 }
 
 // SetAddrHeader sets an address related header field of the Msg
-func (m *Msg) SetAddrHeader(h AddrHeader, v ...string) error {
+func (m *Msg) SetAddrHeader(header AddrHeader, values ...string) error {
 	if m.addrHeader == nil {
 		m.addrHeader = make(map[AddrHeader][]*mail.Address)
 	}
-	var al []*mail.Address
-	for _, av := range v {
-		a, err := mail.ParseAddress(av)
+	var addresses []*mail.Address
+	for _, addrVal := range values {
+		address, err := mail.ParseAddress(addrVal)
 		if err != nil {
-			return fmt.Errorf(errParseMailAddr, av, err)
+			return fmt.Errorf(errParseMailAddr, addrVal, err)
 		}
-		al = append(al, a)
+		addresses = append(addresses, address)
 	}
-	switch h {
+	switch header {
 	case HeaderFrom:
-		if len(al) > 0 {
-			m.addrHeader[h] = []*mail.Address{al[0]}
+		if len(addresses) > 0 {
+			m.addrHeader[header] = []*mail.Address{addresses[0]}
 		}
 	default:
-		m.addrHeader[h] = al
+		m.addrHeader[header] = addresses
 	}
 	return nil
 }
 
 // SetAddrHeaderIgnoreInvalid sets an address related header field of the Msg and ignores invalid address
 // in the validation process
-func (m *Msg) SetAddrHeaderIgnoreInvalid(h AddrHeader, v ...string) {
-	var al []*mail.Address
-	for _, av := range v {
-		a, err := mail.ParseAddress(m.encodeString(av))
+func (m *Msg) SetAddrHeaderIgnoreInvalid(header AddrHeader, values ...string) {
+	var addresses []*mail.Address
+	for _, addrVal := range values {
+		address, err := mail.ParseAddress(m.encodeString(addrVal))
 		if err != nil {
 			continue
 		}
-		al = append(al, a)
+		addresses = append(addresses, address)
 	}
-	m.addrHeader[h] = al
+	m.addrHeader[header] = addresses
 }
 
 // EnvelopeFrom takes and validates a given mail address and sets it as envelope "FROM"
 // addrHeader of the Msg
-func (m *Msg) EnvelopeFrom(f string) error {
-	return m.SetAddrHeader(HeaderEnvelopeFrom, f)
+func (m *Msg) EnvelopeFrom(from string) error {
+	return m.SetAddrHeader(HeaderEnvelopeFrom, from)
 }
 
 // EnvelopeFromFormat takes a name and address, formats them RFC5322 compliant and stores them as
 // the envelope FROM address header field
-func (m *Msg) EnvelopeFromFormat(n, a string) error {
-	return m.SetAddrHeader(HeaderEnvelopeFrom, fmt.Sprintf(`"%s" <%s>`, n, a))
+func (m *Msg) EnvelopeFromFormat(name, addr string) error {
+	return m.SetAddrHeader(HeaderEnvelopeFrom, fmt.Sprintf(`"%s" <%s>`, name, addr))
 }
 
 // From takes and validates a given mail address and sets it as "From" genHeader of the Msg
-func (m *Msg) From(f string) error {
-	return m.SetAddrHeader(HeaderFrom, f)
+func (m *Msg) From(from string) error {
+	return m.SetAddrHeader(HeaderFrom, from)
 }
 
 // FromFormat takes a name and address, formats them RFC5322 compliant and stores them as
 // the From address header field
-func (m *Msg) FromFormat(n, a string) error {
-	return m.SetAddrHeader(HeaderFrom, fmt.Sprintf(`"%s" <%s>`, n, a))
+func (m *Msg) FromFormat(name, addr string) error {
+	return m.SetAddrHeader(HeaderFrom, fmt.Sprintf(`"%s" <%s>`, name, addr))
 }
 
 // To takes and validates a given mail address list sets the To: addresses of the Msg
-func (m *Msg) To(t ...string) error {
-	return m.SetAddrHeader(HeaderTo, t...)
+func (m *Msg) To(rcpts ...string) error {
+	return m.SetAddrHeader(HeaderTo, rcpts...)
 }
 
 // AddTo adds an additional address to the To address header field
-func (m *Msg) AddTo(t string) error {
-	return m.addAddr(HeaderTo, t)
+func (m *Msg) AddTo(rcpt string) error {
+	return m.addAddr(HeaderTo, rcpt)
 }
 
 // AddToFormat takes a name and address, formats them RFC5322 compliant and stores them as
 // as additional To address header field
-func (m *Msg) AddToFormat(n, a string) error {
-	return m.addAddr(HeaderTo, fmt.Sprintf(`"%s" <%s>`, n, a))
+func (m *Msg) AddToFormat(name, addr string) error {
+	return m.addAddr(HeaderTo, fmt.Sprintf(`"%s" <%s>`, name, addr))
 }
 
 // ToIgnoreInvalid takes and validates a given mail address list sets the To: addresses of the Msg
 // Any provided address that is not RFC5322 compliant, will be ignored
-func (m *Msg) ToIgnoreInvalid(t ...string) {
-	m.SetAddrHeaderIgnoreInvalid(HeaderTo, t...)
+func (m *Msg) ToIgnoreInvalid(rcpts ...string) {
+	m.SetAddrHeaderIgnoreInvalid(HeaderTo, rcpts...)
 }
 
 // ToFromString takes and validates a given string of comma separted
 // mail address and sets them as To: addresses of the Msg
-func (m *Msg) ToFromString(v string) error {
-	return m.To(strings.Split(v, ",")...)
+func (m *Msg) ToFromString(rcpts string) error {
+	return m.To(strings.Split(rcpts, ",")...)
 }
 
 // Cc takes and validates a given mail address list sets the Cc: addresses of the Msg
-func (m *Msg) Cc(c ...string) error {
-	return m.SetAddrHeader(HeaderCc, c...)
+func (m *Msg) Cc(rcpts ...string) error {
+	return m.SetAddrHeader(HeaderCc, rcpts...)
 }
 
 // AddCc adds an additional address to the Cc address header field
-func (m *Msg) AddCc(t string) error {
-	return m.addAddr(HeaderCc, t)
+func (m *Msg) AddCc(rcpt string) error {
+	return m.addAddr(HeaderCc, rcpt)
 }
 
 // AddCcFormat takes a name and address, formats them RFC5322 compliant and stores them as
 // as additional Cc address header field
-func (m *Msg) AddCcFormat(n, a string) error {
-	return m.addAddr(HeaderCc, fmt.Sprintf(`"%s" <%s>`, n, a))
+func (m *Msg) AddCcFormat(name, addr string) error {
+	return m.addAddr(HeaderCc, fmt.Sprintf(`"%s" <%s>`, name, addr))
 }
 
 // CcIgnoreInvalid takes and validates a given mail address list sets the Cc: addresses of the Msg
 // Any provided address that is not RFC5322 compliant, will be ignored
-func (m *Msg) CcIgnoreInvalid(c ...string) {
-	m.SetAddrHeaderIgnoreInvalid(HeaderCc, c...)
+func (m *Msg) CcIgnoreInvalid(rcpts ...string) {
+	m.SetAddrHeaderIgnoreInvalid(HeaderCc, rcpts...)
 }
 
 // CcFromString takes and validates a given string of comma separted
 // mail address and sets them as Cc: addresses of the Msg
-func (m *Msg) CcFromString(v string) error {
-	return m.Cc(strings.Split(v, ",")...)
+func (m *Msg) CcFromString(rcpts string) error {
+	return m.Cc(strings.Split(rcpts, ",")...)
 }
 
 // Bcc takes and validates a given mail address list sets the Bcc: addresses of the Msg
-func (m *Msg) Bcc(b ...string) error {
-	return m.SetAddrHeader(HeaderBcc, b...)
+func (m *Msg) Bcc(rcpts ...string) error {
+	return m.SetAddrHeader(HeaderBcc, rcpts...)
 }
 
 // AddBcc adds an additional address to the Bcc address header field
-func (m *Msg) AddBcc(t string) error {
-	return m.addAddr(HeaderBcc, t)
+func (m *Msg) AddBcc(rcpt string) error {
+	return m.addAddr(HeaderBcc, rcpt)
 }
 
 // AddBccFormat takes a name and address, formats them RFC5322 compliant and stores them as
 // as additional Bcc address header field
-func (m *Msg) AddBccFormat(n, a string) error {
-	return m.addAddr(HeaderBcc, fmt.Sprintf(`"%s" <%s>`, n, a))
+func (m *Msg) AddBccFormat(name, addr string) error {
+	return m.addAddr(HeaderBcc, fmt.Sprintf(`"%s" <%s>`, name, addr))
 }
 
 // BccIgnoreInvalid takes and validates a given mail address list sets the Bcc: addresses of the Msg
 // Any provided address that is not RFC5322 compliant, will be ignored
-func (m *Msg) BccIgnoreInvalid(b ...string) {
-	m.SetAddrHeaderIgnoreInvalid(HeaderBcc, b...)
+func (m *Msg) BccIgnoreInvalid(rcpts ...string) {
+	m.SetAddrHeaderIgnoreInvalid(HeaderBcc, rcpts...)
 }
 
 // BccFromString takes and validates a given string of comma separted
 // mail address and sets them as Bcc: addresses of the Msg
-func (m *Msg) BccFromString(v string) error {
-	return m.Bcc(strings.Split(v, ",")...)
+func (m *Msg) BccFromString(rcpts string) error {
+	return m.Bcc(strings.Split(rcpts, ",")...)
 }
 
 // ReplyTo takes and validates a given mail address and sets it as "Reply-To" addrHeader of the Msg
-func (m *Msg) ReplyTo(r string) error {
-	rt, err := mail.ParseAddress(r)
+func (m *Msg) ReplyTo(addr string) error {
+	replyTo, err := mail.ParseAddress(addr)
 	if err != nil {
 		return fmt.Errorf("failed to parse reply-to address: %w", err)
 	}
-	m.SetGenHeader(HeaderReplyTo, rt.String())
+	m.SetGenHeader(HeaderReplyTo, replyTo.String())
 	return nil
 }
 
 // ReplyToFormat takes a name and address, formats them RFC5322 compliant and stores them as
 // the Reply-To header field
-func (m *Msg) ReplyToFormat(n, a string) error {
-	return m.ReplyTo(fmt.Sprintf(`"%s" <%s>`, n, a))
+func (m *Msg) ReplyToFormat(name, addr string) error {
+	return m.ReplyTo(fmt.Sprintf(`"%s" <%s>`, name, addr))
 }
 
 // addAddr adds an additional address to the given addrHeader of the Msg
-func (m *Msg) addAddr(h AddrHeader, a string) error {
-	var al []string
-	for _, ca := range m.addrHeader[h] {
-		al = append(al, ca.String())
+func (m *Msg) addAddr(header AddrHeader, addr string) error {
+	var addresses []string
+	for _, address := range m.addrHeader[header] {
+		addresses = append(addresses, address.String())
 	}
-	al = append(al, a)
-	return m.SetAddrHeader(h, al...)
+	addresses = append(addresses, addr)
+	return m.SetAddrHeader(header, addresses...)
 }
 
 // Subject sets the "Subject" header field of the Msg
-func (m *Msg) Subject(s string) {
-	m.SetGenHeader(HeaderSubject, s)
+func (m *Msg) Subject(subj string) {
+	m.SetGenHeader(HeaderSubject, subj)
 }
 
 // SetMessageID generates a random message id for the mail
 func (m *Msg) SetMessageID() {
-	hn, err := os.Hostname()
+	hostname, err := os.Hostname()
 	if err != nil {
-		hn = "localhost.localdomain"
+		hostname = "localhost.localdomain"
 	}
-	rn, _ := randNum(100000000)
-	rm, _ := randNum(10000)
-	rs, _ := randomStringSecure(17)
-	pid := os.Getpid() * rm
-	mid := fmt.Sprintf("%d.%d%d.%s@%s", pid, rn, rm, rs, hn)
-	m.SetMessageIDWithValue(mid)
+	randNumPrimary, _ := randNum(100000000)
+	randNumSecondary, _ := randNum(10000)
+	randString, _ := randomStringSecure(17)
+	procID := os.Getpid() * randNumSecondary
+	messageID := fmt.Sprintf("%d.%d%d.%s@%s", procID, randNumPrimary, randNumSecondary,
+		randString, hostname)
+	m.SetMessageIDWithValue(messageID)
 }
 
 // SetMessageIDWithValue sets the message id for the mail
-func (m *Msg) SetMessageIDWithValue(v string) {
-	m.SetGenHeader(HeaderMessageID, fmt.Sprintf("<%s>", v))
+func (m *Msg) SetMessageIDWithValue(messageID string) {
+	m.SetGenHeader(HeaderMessageID, fmt.Sprintf("<%s>", messageID))
 }
 
 // SetBulk sets the "Precedence: bulk" and "X-Auto-Response-Suppress: All" genHeaders which are
@@ -481,35 +482,35 @@ func (m *Msg) SetBulk() {
 
 // SetDate sets the Date genHeader field to the current time in a valid format
 func (m *Msg) SetDate() {
-	ts := time.Now().Format(time.RFC1123Z)
-	m.SetGenHeader(HeaderDate, ts)
+	now := time.Now().Format(time.RFC1123Z)
+	m.SetGenHeader(HeaderDate, now)
 }
 
 // SetDateWithValue sets the Date genHeader field to the provided time in a valid format
-func (m *Msg) SetDateWithValue(t time.Time) {
-	m.SetGenHeader(HeaderDate, t.Format(time.RFC1123Z))
+func (m *Msg) SetDateWithValue(timeVal time.Time) {
+	m.SetGenHeader(HeaderDate, timeVal.Format(time.RFC1123Z))
 }
 
 // SetImportance sets the Msg Importance/Priority header to given Importance
-func (m *Msg) SetImportance(i Importance) {
-	if i == ImportanceNormal {
+func (m *Msg) SetImportance(importance Importance) {
+	if importance == ImportanceNormal {
 		return
 	}
-	m.SetGenHeader(HeaderImportance, i.String())
-	m.SetGenHeader(HeaderPriority, i.NumString())
-	m.SetGenHeader(HeaderXPriority, i.XPrioString())
-	m.SetGenHeader(HeaderXMSMailPriority, i.NumString())
+	m.SetGenHeader(HeaderImportance, importance.String())
+	m.SetGenHeader(HeaderPriority, importance.NumString())
+	m.SetGenHeader(HeaderXPriority, importance.XPrioString())
+	m.SetGenHeader(HeaderXMSMailPriority, importance.NumString())
 }
 
 // SetOrganization sets the provided string as Organization header for the Msg
-func (m *Msg) SetOrganization(o string) {
-	m.SetGenHeader(HeaderOrganization, o)
+func (m *Msg) SetOrganization(org string) {
+	m.SetGenHeader(HeaderOrganization, org)
 }
 
 // SetUserAgent sets the User-Agent/X-Mailer header for the Msg
-func (m *Msg) SetUserAgent(a string) {
-	m.SetGenHeader(HeaderUserAgent, a)
-	m.SetGenHeader(HeaderXMailer, a)
+func (m *Msg) SetUserAgent(userAgent string) {
+	m.SetGenHeader(HeaderUserAgent, userAgent)
+	m.SetGenHeader(HeaderXMailer, userAgent)
 }
 
 // IsDelivered will return true if the Msg has been successfully delivered
@@ -521,17 +522,17 @@ func (m *Msg) IsDelivered() bool {
 // as described in RFC8098. It allows to provide a list recipient addresses.
 // Address validation is performed
 // See: https://www.rfc-editor.org/rfc/rfc8098.html
-func (m *Msg) RequestMDNTo(t ...string) error {
-	var tl []string
-	for _, at := range t {
-		a, err := mail.ParseAddress(at)
+func (m *Msg) RequestMDNTo(rcpts ...string) error {
+	var addresses []string
+	for _, addrVal := range rcpts {
+		address, err := mail.ParseAddress(addrVal)
 		if err != nil {
-			return fmt.Errorf(errParseMailAddr, at, err)
+			return fmt.Errorf(errParseMailAddr, addrVal, err)
 		}
-		tl = append(tl, a.String())
+		addresses = append(addresses, address.String())
 	}
 	if _, ok := m.genHeader[HeaderDispositionNotificationTo]; ok {
-		m.genHeader[HeaderDispositionNotificationTo] = tl
+		m.genHeader[HeaderDispositionNotificationTo] = addresses
 	}
 	return nil
 }
@@ -540,77 +541,77 @@ func (m *Msg) RequestMDNTo(t ...string) error {
 // as described in RFC8098. It allows to provide a recipient address with name and address and will format
 // accordingly. Address validation is performed
 // See: https://www.rfc-editor.org/rfc/rfc8098.html
-func (m *Msg) RequestMDNToFormat(n, a string) error {
-	return m.RequestMDNTo(fmt.Sprintf(`%s <%s>`, n, a))
+func (m *Msg) RequestMDNToFormat(name, addr string) error {
+	return m.RequestMDNTo(fmt.Sprintf(`%s <%s>`, name, addr))
 }
 
 // RequestMDNAddTo adds an additional recipient to the recipient list of the MDN
-func (m *Msg) RequestMDNAddTo(t string) error {
-	a, err := mail.ParseAddress(t)
+func (m *Msg) RequestMDNAddTo(rcpt string) error {
+	address, err := mail.ParseAddress(rcpt)
 	if err != nil {
-		return fmt.Errorf(errParseMailAddr, t, err)
+		return fmt.Errorf(errParseMailAddr, rcpt, err)
 	}
-	var tl []string
-	tl = append(tl, m.genHeader[HeaderDispositionNotificationTo]...)
-	tl = append(tl, a.String())
+	var addresses []string
+	addresses = append(addresses, m.genHeader[HeaderDispositionNotificationTo]...)
+	addresses = append(addresses, address.String())
 	if _, ok := m.genHeader[HeaderDispositionNotificationTo]; ok {
-		m.genHeader[HeaderDispositionNotificationTo] = tl
+		m.genHeader[HeaderDispositionNotificationTo] = addresses
 	}
 	return nil
 }
 
 // RequestMDNAddToFormat adds an additional formated recipient to the recipient list of the MDN
-func (m *Msg) RequestMDNAddToFormat(n, a string) error {
-	return m.RequestMDNAddTo(fmt.Sprintf(`"%s" <%s>`, n, a))
+func (m *Msg) RequestMDNAddToFormat(name, addr string) error {
+	return m.RequestMDNAddTo(fmt.Sprintf(`"%s" <%s>`, name, addr))
 }
 
 // GetSender returns the currently set envelope FROM address. If no envelope FROM is set it will use
-// the first mail body FROM address. If ff is true, it will return the full address string including
-// the address name, if set
-func (m *Msg) GetSender(ff bool) (string, error) {
-	f, ok := m.addrHeader[HeaderEnvelopeFrom]
-	if !ok || len(f) == 0 {
-		f, ok = m.addrHeader[HeaderFrom]
-		if !ok || len(f) == 0 {
+// the first mail body FROM address. If useFullAddr is true, it will return the full address string
+// including the address name, if set
+func (m *Msg) GetSender(useFullAddr bool) (string, error) {
+	from, ok := m.addrHeader[HeaderEnvelopeFrom]
+	if !ok || len(from) == 0 {
+		from, ok = m.addrHeader[HeaderFrom]
+		if !ok || len(from) == 0 {
 			return "", ErrNoFromAddress
 		}
 	}
-	if ff {
-		return f[0].String(), nil
+	if useFullAddr {
+		return from[0].String(), nil
 	}
-	return f[0].Address, nil
+	return from[0].Address, nil
 }
 
 // GetRecipients returns a list of the currently set TO/CC/BCC addresses.
 func (m *Msg) GetRecipients() ([]string, error) {
-	var rl []string
-	for _, t := range []AddrHeader{HeaderTo, HeaderCc, HeaderBcc} {
-		al, ok := m.addrHeader[t]
-		if !ok || len(al) == 0 {
+	var rcpts []string
+	for _, addressType := range []AddrHeader{HeaderTo, HeaderCc, HeaderBcc} {
+		addresses, ok := m.addrHeader[addressType]
+		if !ok || len(addresses) == 0 {
 			continue
 		}
-		for _, r := range al {
-			rl = append(rl, r.Address)
+		for _, r := range addresses {
+			rcpts = append(rcpts, r.Address)
 		}
 	}
-	if len(rl) <= 0 {
-		return rl, ErrNoRcptAddresses
+	if len(rcpts) <= 0 {
+		return rcpts, ErrNoRcptAddresses
 	}
-	return rl, nil
+	return rcpts, nil
 }
 
 // GetAddrHeader returns the content of the requested address header of the Msg
-func (m *Msg) GetAddrHeader(h AddrHeader) []*mail.Address {
-	return m.addrHeader[h]
+func (m *Msg) GetAddrHeader(header AddrHeader) []*mail.Address {
+	return m.addrHeader[header]
 }
 
 // GetAddrHeaderString returns the address string of the requested address header of the Msg
-func (m *Msg) GetAddrHeaderString(h AddrHeader) []string {
-	var al []string
-	for _, mh := range m.addrHeader[h] {
-		al = append(al, mh.String())
+func (m *Msg) GetAddrHeaderString(header AddrHeader) []string {
+	var addresses []string
+	for _, mh := range m.addrHeader[header] {
+		addresses = append(addresses, mh.String())
 	}
-	return al
+	return addresses
 }
 
 // GetFrom returns the content of the From address header of the Msg
@@ -654,8 +655,8 @@ func (m *Msg) GetBccString() []string {
 }
 
 // GetGenHeader returns the content of the requested generic header of the Msg
-func (m *Msg) GetGenHeader(h Header) []string {
-	return m.genHeader[h]
+func (m *Msg) GetGenHeader(header Header) []string {
+	return m.genHeader[header]
 }
 
 // GetParts returns the message parts of the Msg
@@ -669,8 +670,8 @@ func (m *Msg) GetAttachments() []*File {
 }
 
 // SetAttachements sets the attachements of the message.
-func (m *Msg) SetAttachements(ff []*File) {
-	m.attachments = ff
+func (m *Msg) SetAttachements(files []*File) {
+	m.attachments = files
 }
 
 // UnsetAllAttachments unset the attachments of the message.
@@ -684,8 +685,8 @@ func (m *Msg) GetEmbeds() []*File {
 }
 
 // SetEmbeds sets the embeds of the message.
-func (m *Msg) SetEmbeds(ff []*File) {
-	m.embeds = ff
+func (m *Msg) SetEmbeds(files []*File) {
+	m.embeds = files
 }
 
 // UnsetAllEmbeds unset the embeds of the message.
@@ -700,16 +701,16 @@ func (m *Msg) UnsetAllParts() {
 }
 
 // SetBodyString sets the body of the message.
-func (m *Msg) SetBodyString(ct ContentType, b string, o ...PartOption) {
-	buf := bytes.NewBufferString(b)
-	w := writeFuncFromBuffer(buf)
-	m.SetBodyWriter(ct, w, o...)
+func (m *Msg) SetBodyString(contentType ContentType, content string, opts ...PartOption) {
+	buffer := bytes.NewBufferString(content)
+	writeFunc := writeFuncFromBuffer(buffer)
+	m.SetBodyWriter(contentType, writeFunc, opts...)
 }
 
 // SetBodyWriter sets the body of the message.
-func (m *Msg) SetBodyWriter(ct ContentType, w func(io.Writer) (int64, error), o ...PartOption) {
-	p := m.newPart(ct, o...)
-	p.w = w
+func (m *Msg) SetBodyWriter(contentType ContentType, writeFunc func(io.Writer) (int64, error), opts ...PartOption) {
+	p := m.newPart(contentType, opts...)
+	p.w = writeFunc
 	m.parts = []*Part{p}
 }
 
@@ -933,9 +934,9 @@ func (m *Msg) applyMiddlewares(ms *Msg) *Msg {
 
 // WriteTo writes the formated Msg into a give io.Writer and satisfies the io.WriteTo interface
 func (m *Msg) WriteTo(w io.Writer) (int64, error) {
-	mw := &msgWriter{w: w, c: m.charset, en: m.encoder}
+	mw := &msgWriter{writer: w, charset: m.charset, encoder: m.encoder}
 	mw.writeMsg(m.applyMiddlewares(m))
-	return mw.n, mw.err
+	return mw.bytesWritten, mw.err
 }
 
 // WriteToSkipMiddleware writes the formated Msg into a give io.Writer and satisfies
@@ -950,10 +951,10 @@ func (m *Msg) WriteToSkipMiddleware(w io.Writer, mt MiddlewareType) (int64, erro
 		mwl = append(mwl, m.middlewares[i])
 	}
 	m.middlewares = mwl
-	mw := &msgWriter{w: w, c: m.charset, en: m.encoder}
+	mw := &msgWriter{writer: w, charset: m.charset, encoder: m.encoder}
 	mw.writeMsg(m.applyMiddlewares(m))
 	m.middlewares = omwl
-	return mw.n, mw.err
+	return mw.bytesWritten, mw.err
 }
 
 // Write is an alias method to WriteTo due to compatibility reasons

msgwriter.go

@@ -35,237 +35,241 @@ const DoubleNewLine = "\r\n\r\n"
 
 // msgWriter handles the I/O to the io.WriteCloser of the SMTP client
 type msgWriter struct {
-	c   Charset
-	d   int8
-	en  mime.WordEncoder
+	bytesWritten    int64
+	charset         Charset
+	depth           int8
+	encoder         mime.WordEncoder
 	err             error
-	mpw [3]*multipart.Writer
-	n   int64
-	pw  io.Writer
-	w   io.Writer
+	multiPartWriter [3]*multipart.Writer
+	partWriter      io.Writer
+	writer          io.Writer
 }
 
 // Write implements the io.Writer interface for msgWriter
-func (mw *msgWriter) Write(p []byte) (int, error) {
+func (mw *msgWriter) Write(payload []byte) (int, error) {
 	if mw.err != nil {
 		return 0, fmt.Errorf("failed to write due to previous error: %w", mw.err)
 	}
 
 	var n int
-	n, mw.err = mw.w.Write(p)
-	mw.n += int64(n)
+	n, mw.err = mw.writer.Write(payload)
+	mw.bytesWritten += int64(n)
 	return n, mw.err
 }
 
 // writeMsg formats the message and sends it to its io.Writer
-func (mw *msgWriter) writeMsg(m *Msg) {
-	m.addDefaultHeader()
-	m.checkUserAgent()
-	mw.writeGenHeader(m)
-	mw.writePreformattedGenHeader(m)
+func (mw *msgWriter) writeMsg(msg *Msg) {
+	msg.addDefaultHeader()
+	msg.checkUserAgent()
+	mw.writeGenHeader(msg)
+	mw.writePreformattedGenHeader(msg)
 
 	// Set the FROM header (or envelope FROM if FROM is empty)
-	hf := true
-	f, ok := m.addrHeader[HeaderFrom]
-	if !ok || (len(f) == 0 || f == nil) {
-		f, ok = m.addrHeader[HeaderEnvelopeFrom]
-		if !ok || (len(f) == 0 || f == nil) {
-			hf = false
+	hasFrom := true
+	from, ok := msg.addrHeader[HeaderFrom]
+	if !ok || (len(from) == 0 || from == nil) {
+		from, ok = msg.addrHeader[HeaderEnvelopeFrom]
+		if !ok || (len(from) == 0 || from == nil) {
+			hasFrom = false
 		}
 	}
-	if hf && (len(f) > 0 && f[0] != nil) {
-		mw.writeHeader(Header(HeaderFrom), f[0].String())
+	if hasFrom && (len(from) > 0 && from[0] != nil) {
+		mw.writeHeader(Header(HeaderFrom), from[0].String())
 	}
 
 	// Set the rest of the address headers
-	for _, t := range []AddrHeader{HeaderTo, HeaderCc} {
-		if al, ok := m.addrHeader[t]; ok {
-			var v []string
-			for _, a := range al {
-				v = append(v, a.String())
+	for _, to := range []AddrHeader{HeaderTo, HeaderCc} {
+		if addresses, ok := msg.addrHeader[to]; ok {
+			var val []string
+			for _, addr := range addresses {
+				val = append(val, addr.String())
 			}
-			mw.writeHeader(Header(t), v...)
+			mw.writeHeader(Header(to), val...)
 		}
 	}
 
-	if m.hasMixed() {
-		mw.startMP("mixed", m.boundary)
+	if msg.hasMixed() {
+		mw.startMP("mixed", msg.boundary)
 		mw.writeString(DoubleNewLine)
 	}
-	if m.hasRelated() {
-		mw.startMP("related", m.boundary)
+	if msg.hasRelated() {
+		mw.startMP("related", msg.boundary)
 		mw.writeString(DoubleNewLine)
 	}
-	if m.hasAlt() {
-		mw.startMP(MIMEAlternative, m.boundary)
+	if msg.hasAlt() {
+		mw.startMP(MIMEAlternative, msg.boundary)
 		mw.writeString(DoubleNewLine)
 	}
-	if m.hasPGPType() {
-		switch m.pgptype {
+	if msg.hasPGPType() {
+		switch msg.pgptype {
 		case PGPEncrypt:
-			mw.startMP(`encrypted; protocol="application/pgp-encrypted"`, m.boundary)
+			mw.startMP(`encrypted; protocol="application/pgp-encrypted"`,
+				msg.boundary)
 		case PGPSignature:
-			mw.startMP(`signed; protocol="application/pgp-signature";`, m.boundary)
+			mw.startMP(`signed; protocol="application/pgp-signature";`,
+				msg.boundary)
+		default:
 		}
 		mw.writeString(DoubleNewLine)
 	}
 
-	for _, p := range m.parts {
-		if !p.del {
-			mw.writePart(p, m.charset)
+	for _, part := range msg.parts {
+		if !part.del {
+			mw.writePart(part, msg.charset)
 		}
 	}
 
-	if m.hasAlt() {
+	if msg.hasAlt() {
 		mw.stopMP()
 	}
 
 	// Add embeds
-	mw.addFiles(m.embeds, false)
-	if m.hasRelated() {
+	mw.addFiles(msg.embeds, false)
+	if msg.hasRelated() {
 		mw.stopMP()
 	}
 
 	// Add attachments
-	mw.addFiles(m.attachments, true)
-	if m.hasMixed() {
+	mw.addFiles(msg.attachments, true)
+	if msg.hasMixed() {
 		mw.stopMP()
 	}
 }
 
 // writeGenHeader writes out all generic headers to the msgWriter
-func (mw *msgWriter) writeGenHeader(m *Msg) {
-	gk := make([]string, 0, len(m.genHeader))
-	for k := range m.genHeader {
-		gk = append(gk, string(k))
+func (mw *msgWriter) writeGenHeader(msg *Msg) {
+	keys := make([]string, 0, len(msg.genHeader))
+	for key := range msg.genHeader {
+		keys = append(keys, string(key))
 	}
-	sort.Strings(gk)
-	for _, k := range gk {
-		mw.writeHeader(Header(k), m.genHeader[Header(k)]...)
+	sort.Strings(keys)
+	for _, key := range keys {
+		mw.writeHeader(Header(key), msg.genHeader[Header(key)]...)
 	}
 }
 
 // writePreformatedHeader writes out all preformated generic headers to the msgWriter
-func (mw *msgWriter) writePreformattedGenHeader(m *Msg) {
-	for k, v := range m.preformHeader {
-		mw.writeString(fmt.Sprintf("%s: %s%s", k, v, SingleNewLine))
+func (mw *msgWriter) writePreformattedGenHeader(msg *Msg) {
+	for key, val := range msg.preformHeader {
+		mw.writeString(fmt.Sprintf("%s: %s%s", key, val, SingleNewLine))
 	}
 }
 
 // startMP writes a multipart beginning
-func (mw *msgWriter) startMP(mt MIMEType, b string) {
-	mp := multipart.NewWriter(mw)
-	if b != "" {
-		mw.err = mp.SetBoundary(b)
+func (mw *msgWriter) startMP(mimeType MIMEType, boundary string) {
+	multiPartWriter := multipart.NewWriter(mw)
+	if boundary != "" {
+		mw.err = multiPartWriter.SetBoundary(boundary)
 	}
 
-	ct := fmt.Sprintf("multipart/%s;\r\n boundary=%s", mt, mp.Boundary())
-	mw.mpw[mw.d] = mp
+	contentType := fmt.Sprintf("multipart/%s;\r\n boundary=%s", mimeType,
+		multiPartWriter.Boundary())
+	mw.multiPartWriter[mw.depth] = multiPartWriter
 
-	if mw.d == 0 {
-		mw.writeString(fmt.Sprintf("%s: %s", HeaderContentType, ct))
+	if mw.depth == 0 {
+		mw.writeString(fmt.Sprintf("%s: %s", HeaderContentType, contentType))
 	}
-	if mw.d > 0 {
-		mw.newPart(map[string][]string{"Content-Type": {ct}})
+	if mw.depth > 0 {
+		mw.newPart(map[string][]string{"Content-Type": {contentType}})
 	}
-	mw.d++
+	mw.depth++
 }
 
 // stopMP closes the multipart
 func (mw *msgWriter) stopMP() {
-	if mw.d > 0 {
-		mw.err = mw.mpw[mw.d-1].Close()
-		mw.d--
+	if mw.depth > 0 {
+		mw.err = mw.multiPartWriter[mw.depth-1].Close()
+		mw.depth--
 	}
 }
 
 // addFiles adds the attachments/embeds file content to the mail body
-func (mw *msgWriter) addFiles(fl []*File, a bool) {
-	for _, f := range fl {
-		e := EncodingB64
-		if _, ok := f.getHeader(HeaderContentType); !ok {
-			mt := mime.TypeByExtension(filepath.Ext(f.Name))
-			if mt == "" {
-				mt = "application/octet-stream"
+func (mw *msgWriter) addFiles(files []*File, isAttachment bool) {
+	for _, file := range files {
+		encoding := EncodingB64
+		if _, ok := file.getHeader(HeaderContentType); !ok {
+			mimeType := mime.TypeByExtension(filepath.Ext(file.Name))
+			if mimeType == "" {
+				mimeType = "application/octet-stream"
 			}
-			if f.ContentType != "" {
-				mt = string(f.ContentType)
+			if file.ContentType != "" {
+				mimeType = string(file.ContentType)
 			}
-			f.setHeader(HeaderContentType, fmt.Sprintf(`%s; name="%s"`, mt,
-				mw.en.Encode(mw.c.String(), f.Name)))
+			file.setHeader(HeaderContentType, fmt.Sprintf(`%s; name="%s"`, mimeType,
+				mw.encoder.Encode(mw.charset.String(), file.Name)))
 		}
 
-		if _, ok := f.getHeader(HeaderContentTransferEnc); !ok {
-			if f.Enc != "" {
-				e = f.Enc
+		if _, ok := file.getHeader(HeaderContentTransferEnc); !ok {
+			if file.Enc != "" {
+				encoding = file.Enc
 			}
-			f.setHeader(HeaderContentTransferEnc, string(e))
+			file.setHeader(HeaderContentTransferEnc, string(encoding))
 		}
 
-		if f.Desc != "" {
-			if _, ok := f.getHeader(HeaderContentDescription); !ok {
-				f.setHeader(HeaderContentDescription, f.Desc)
+		if file.Desc != "" {
+			if _, ok := file.getHeader(HeaderContentDescription); !ok {
+				file.setHeader(HeaderContentDescription, file.Desc)
 			}
 		}
 
-		if _, ok := f.getHeader(HeaderContentDisposition); !ok {
-			d := "inline"
-			if a {
-				d = "attachment"
+		if _, ok := file.getHeader(HeaderContentDisposition); !ok {
+			disposition := "inline"
+			if isAttachment {
+				disposition = "attachment"
 			}
-			f.setHeader(HeaderContentDisposition, fmt.Sprintf(`%s; filename="%s"`, d,
-				mw.en.Encode(mw.c.String(), f.Name)))
+			file.setHeader(HeaderContentDisposition, fmt.Sprintf(`%s; filename="%s"`,
+				disposition, mw.encoder.Encode(mw.charset.String(), file.Name)))
 		}
 
-		if !a {
-			if _, ok := f.getHeader(HeaderContentID); !ok {
-				f.setHeader(HeaderContentID, fmt.Sprintf("<%s>", f.Name))
+		if !isAttachment {
+			if _, ok := file.getHeader(HeaderContentID); !ok {
+				file.setHeader(HeaderContentID, fmt.Sprintf("<%s>", file.Name))
 			}
 		}
-		if mw.d == 0 {
-			for h, v := range f.Header {
-				mw.writeHeader(Header(h), v...)
+		if mw.depth == 0 {
+			for header, val := range file.Header {
+				mw.writeHeader(Header(header), val...)
 			}
 			mw.writeString(SingleNewLine)
 		}
-		if mw.d > 0 {
-			mw.newPart(f.Header)
+		if mw.depth > 0 {
+			mw.newPart(file.Header)
 		}
 
 		if mw.err == nil {
-			mw.writeBody(f.Writer, e)
+			mw.writeBody(file.Writer, encoding)
 		}
 	}
 }
 
 // newPart creates a new MIME multipart io.Writer and sets the partwriter to it
-func (mw *msgWriter) newPart(h map[string][]string) {
-	mw.pw, mw.err = mw.mpw[mw.d-1].CreatePart(h)
+func (mw *msgWriter) newPart(header map[string][]string) {
+	mw.partWriter, mw.err = mw.multiPartWriter[mw.depth-1].CreatePart(header)
 }
 
 // writePart writes the corresponding part to the Msg body
-func (mw *msgWriter) writePart(p *Part, cs Charset) {
-	pcs := p.cset
-	if pcs.String() == "" {
-		pcs = cs
+func (mw *msgWriter) writePart(part *Part, charset Charset) {
+	partCharset := part.cset
+	if partCharset.String() == "" {
+		partCharset = charset
 	}
-	ct := fmt.Sprintf("%s; charset=%s", p.ctype, pcs)
-	cte := p.enc.String()
-	if mw.d == 0 {
-		mw.writeHeader(HeaderContentType, ct)
-		mw.writeHeader(HeaderContentTransferEnc, cte)
+	contentType := fmt.Sprintf("%s; charset=%s", part.ctype, partCharset)
+	contentTransferEnc := part.enc.String()
+	if mw.depth == 0 {
+		mw.writeHeader(HeaderContentType, contentType)
+		mw.writeHeader(HeaderContentTransferEnc, contentTransferEnc)
 		mw.writeString(SingleNewLine)
 	}
-	if mw.d > 0 {
-		mh := textproto.MIMEHeader{}
-		if p.desc != "" {
-			mh.Add(string(HeaderContentDescription), p.desc)
+	if mw.depth > 0 {
+		mimeHeader := textproto.MIMEHeader{}
+		if part.desc != "" {
+			mimeHeader.Add(string(HeaderContentDescription), part.desc)
 		}
-		mh.Add(string(HeaderContentType), ct)
-		mh.Add(string(HeaderContentTransferEnc), cte)
-		mw.newPart(mh)
+		mimeHeader.Add(string(HeaderContentType), contentType)
+		mimeHeader.Add(string(HeaderContentTransferEnc), contentTransferEnc)
+		mw.newPart(mimeHeader)
 	}
-	mw.writeBody(p.w, p.enc)
+	mw.writeBody(part.w, part.enc)
 }
 
 // writeString writes a string into the msgWriter's io.Writer interface
@@ -274,102 +278,103 @@ func (mw *msgWriter) writeString(s string) {
 		return
 	}
 	var n int
-	n, mw.err = io.WriteString(mw.w, s)
-	mw.n += int64(n)
+	n, mw.err = io.WriteString(mw.writer, s)
+	mw.bytesWritten += int64(n)
 }
 
 // writeHeader writes a header into the msgWriter's io.Writer
-func (mw *msgWriter) writeHeader(k Header, vl ...string) {
-	wbuf := bytes.Buffer{}
-	cl := MaxHeaderLength - 2
-	wbuf.WriteString(string(k))
-	cl -= len(k)
-	if len(vl) == 0 {
-		wbuf.WriteString(":\r\n")
+func (mw *msgWriter) writeHeader(key Header, values ...string) {
+	buffer := strings.Builder{}
+	charLength := MaxHeaderLength - 2
+	buffer.WriteString(string(key))
+	charLength -= len(key)
+	if len(values) == 0 {
+		buffer.WriteString(":\r\n")
 		return
 	}
-	wbuf.WriteString(": ")
-	cl -= 2
+	buffer.WriteString(": ")
+	charLength -= 2
 
-	fs := strings.Join(vl, ", ")
-	sfs := strings.Split(fs, " ")
-	for i, v := range sfs {
-		if cl-len(v) <= 1 {
-			wbuf.WriteString(fmt.Sprintf("%s ", SingleNewLine))
-			cl = MaxHeaderLength - 3
+	fullValueStr := strings.Join(values, ", ")
+	words := strings.Split(fullValueStr, " ")
+	for i, val := range words {
+		if charLength-len(val) <= 1 {
+			buffer.WriteString(fmt.Sprintf("%s ", SingleNewLine))
+			charLength = MaxHeaderLength - 3
 		}
-		wbuf.WriteString(v)
-		if i < len(sfs)-1 {
-			wbuf.WriteString(" ")
-			cl -= 1
+		buffer.WriteString(val)
+		if i < len(words)-1 {
+			buffer.WriteString(" ")
+			charLength -= 1
 		}
-		cl -= len(v)
+		charLength -= len(val)
 	}
 
-	bufs := wbuf.String()
-	bufs = strings.ReplaceAll(bufs, fmt.Sprintf(" %s", SingleNewLine), SingleNewLine)
-	mw.writeString(bufs)
+	bufferString := buffer.String()
+	bufferString = strings.ReplaceAll(bufferString, fmt.Sprintf(" %s", SingleNewLine),
+		SingleNewLine)
+	mw.writeString(bufferString)
 	mw.writeString("\r\n")
 }
 
 // writeBody writes an io.Reader into an io.Writer using provided Encoding
-func (mw *msgWriter) writeBody(f func(io.Writer) (int64, error), e Encoding) {
-	var w io.Writer
-	var ew io.WriteCloser
+func (mw *msgWriter) writeBody(writeFunc func(io.Writer) (int64, error), encoding Encoding) {
+	var writer io.Writer
+	var encodedWriter io.WriteCloser
 	var n int64
 	var err error
-	if mw.d == 0 {
-		w = mw.w
+	if mw.depth == 0 {
+		writer = mw.writer
 	}
-	if mw.d > 0 {
-		w = mw.pw
+	if mw.depth > 0 {
+		writer = mw.partWriter
 	}
-	wbuf := bytes.Buffer{}
-	lb := Base64LineBreaker{}
-	lb.out = &wbuf
+	writeBuffer := bytes.Buffer{}
+	lineBreaker := Base64LineBreaker{}
+	lineBreaker.out = &writeBuffer
 
-	switch e {
+	switch encoding {
 	case EncodingQP:
-		ew = quotedprintable.NewWriter(&wbuf)
+		encodedWriter = quotedprintable.NewWriter(&writeBuffer)
 	case EncodingB64:
-		ew = base64.NewEncoder(base64.StdEncoding, &lb)
+		encodedWriter = base64.NewEncoder(base64.StdEncoding, &lineBreaker)
 	case NoEncoding:
-		_, err = f(&wbuf)
+		_, err = writeFunc(&writeBuffer)
 		if err != nil {
 			mw.err = fmt.Errorf("bodyWriter function: %w", err)
 		}
-		n, err = io.Copy(w, &wbuf)
+		n, err = io.Copy(writer, &writeBuffer)
 		if err != nil && mw.err == nil {
 			mw.err = fmt.Errorf("bodyWriter io.Copy: %w", err)
 		}
-		if mw.d == 0 {
-			mw.n += n
+		if mw.depth == 0 {
+			mw.bytesWritten += n
 		}
 		return
 	default:
-		ew = quotedprintable.NewWriter(w)
+		encodedWriter = quotedprintable.NewWriter(writer)
 	}
 
-	_, err = f(ew)
+	_, err = writeFunc(encodedWriter)
 	if err != nil {
 		mw.err = fmt.Errorf("bodyWriter function: %w", err)
 	}
-	err = ew.Close()
+	err = encodedWriter.Close()
 	if err != nil && mw.err == nil {
 		mw.err = fmt.Errorf("bodyWriter close encoded writer: %w", err)
 	}
-	err = lb.Close()
+	err = lineBreaker.Close()
 	if err != nil && mw.err == nil {
 		mw.err = fmt.Errorf("bodyWriter close linebreaker: %w", err)
 	}
-	n, err = io.Copy(w, &wbuf)
+	n, err = io.Copy(writer, &writeBuffer)
 	if err != nil && mw.err == nil {
 		mw.err = fmt.Errorf("bodyWriter io.Copy: %w", err)
 	}
 
 	// Since the part writer uses the WriteTo() method, we don't need to add the
 	// bytes twice
-	if mw.d == 0 {
-		mw.n += n
+	if mw.depth == 0 {
+		mw.bytesWritten += n
 	}
 }

msgwriter_test.go

@@ -28,7 +28,7 @@ func (bw *brokenWriter) Write([]byte) (int, error) {
 // TestMsgWriter_Write tests the WriteTo() method of the msgWriter
 func TestMsgWriter_Write(t *testing.T) {
 	bw := &brokenWriter{}
-	mw := &msgWriter{w: bw, c: CharsetUTF8, en: mime.QEncoding}
+	mw := &msgWriter{writer: bw, charset: CharsetUTF8, encoder: mime.QEncoding}
 	_, err := mw.Write([]byte("test"))
 	if err == nil {
 		t.Errorf("msgWriter WriteTo() with brokenWriter should fail, but didn't")
@@ -55,7 +55,7 @@ func TestMsgWriter_writeMsg(t *testing.T) {
 	m.SetBodyString(TypeTextPlain, "This is the body")
 	m.AddAlternativeString(TypeTextHTML, "This is the alternative body")
 	buf := bytes.Buffer{}
-	mw := &msgWriter{w: &buf, c: CharsetUTF8, en: mime.QEncoding}
+	mw := &msgWriter{writer: &buf, charset: CharsetUTF8, encoder: mime.QEncoding}
 	mw.writeMsg(m)
 	ms := buf.String()
 
@@ -134,7 +134,7 @@ func TestMsgWriter_writeMsg_PGP(t *testing.T) {
 	m.Subject("This is a subject")
 	m.SetBodyString(TypeTextPlain, "This is the body")
 	buf := bytes.Buffer{}
-	mw := &msgWriter{w: &buf, c: CharsetUTF8, en: mime.QEncoding}
+	mw := &msgWriter{writer: &buf, charset: CharsetUTF8, encoder: mime.QEncoding}
 	mw.writeMsg(m)
 	ms := buf.String()
 	if !strings.Contains(ms, `encrypted; protocol="application/pgp-encrypted"`) {
@@ -147,7 +147,7 @@ func TestMsgWriter_writeMsg_PGP(t *testing.T) {
 	m.Subject("This is a subject")
 	m.SetBodyString(TypeTextPlain, "This is the body")
 	buf = bytes.Buffer{}
-	mw = &msgWriter{w: &buf, c: CharsetUTF8, en: mime.QEncoding}
+	mw = &msgWriter{writer: &buf, charset: CharsetUTF8, encoder: mime.QEncoding}
 	mw.writeMsg(m)
 	ms = buf.String()
 	if !strings.Contains(ms, `signed; protocol="application/pgp-signature"`) {