Refactor DSN field in Client structure

Renamed `dsn` field to `requestDSN` in Client structure for clarity and consistency. Adjusted associated methods and tests to reflect this change, improving code readability and maintainability.

client.go

@@ -40,19 +40,6 @@ const (
 	DefaultTLSMinVersion = tls.VersionTLS12
 )
 
-type (
-
-	// DSNMailReturnOption is a type wrapper for a string and specifies the type of return content requested
-	// in a Delivery Status Notification (DSN).
-	// https://datatracker.ietf.org/doc/html/rfc1891/
-	DSNMailReturnOption string
-
-	// DSNRcptNotifyOption is a type wrapper for a string and specifies the notification options for a
-	// recipient in DSNs.
-	// https://datatracker.ietf.org/doc/html/rfc1891/
-	DSNRcptNotifyOption string
-)
-
 const (
 
 	// DSNMailReturnHeadersOnly requests that only the message headers of the mail message are returned in
@@ -90,20 +77,35 @@ const (
 	DSNRcptNotifyDelay DSNRcptNotifyOption = "DELAY"
 )
 
-// DialContextFunc is a type to define custom DialContext function.
+type (
-type DialContextFunc func(ctx context.Context, network, address string) (net.Conn, error)
 
-// Client is the SMTP client struct
+	// DialContextFunc defines a function type for establishing a network connection using context, network
-type Client struct {
+	// type, and address. It is used to specify custom DialContext function.
-	// Timeout for the SMTP server connection
+	//
+	// By default we use net.Dial or tls.Dial respectively.
+	DialContextFunc func(ctx context.Context, network, address string) (net.Conn, error)
+
+	// DSNMailReturnOption is a type wrapper for a string and specifies the type of return content requested
+	// in a Delivery Status Notification (DSN).
+	// https://datatracker.ietf.org/doc/html/rfc1891/
+	DSNMailReturnOption string
+
+	// DSNRcptNotifyOption is a type wrapper for a string and specifies the notification options for a
+	// recipient in DSNs.
+	// https://datatracker.ietf.org/doc/html/rfc1891/
+	DSNRcptNotifyOption string
+
+	// Option is a function type that modifies the configuration or behavior of a Client instance.
+	Option func(*Client) error
+
+	// Client is the go-mail client that is responsible for connecting and interacting with an SMTP server.
+	Client struct {
+		// connTimeout specifies timeout for the connection to the SMTP server.
 		connTimeout time.Duration
 
-	// dialContextFunc is a custom DialContext function to dial target SMTP server
+		// dialContextFunc is the DialContextFunc that is used by the Client to connect to the SMTP server.
 		dialContextFunc DialContextFunc
 
-	// dsn indicates that we want to use DSN for the Client
-	dsn bool
-
 		// dsnmrtype defines the DSNMailReturnOption in case DSN is enabled
 		dsnmrtype DSNMailReturnOption
 
@@ -139,6 +141,9 @@ type Client struct {
 		// port specifies the network port number on which the server listens for incoming connections.
 		port int
 
+		// requestDSN indicates that we want to use DSN for the Client
+		requestDSN bool
+
 		// smtpAuth is a pointer to smtp.Auth
 		smtpAuth smtp.Auth
 
@@ -163,9 +168,7 @@ type Client struct {
 		// Use SSL for the connection
 		useSSL bool
 	}
-
+)
-// Option returns a function that can be used for grouping Client options
-type Option func(*Client) error
 
 var (
 	// ErrInvalidPort should be used if a port is specified that is not valid
@@ -394,7 +397,7 @@ func WithPassword(password string) Option {
 // and DSNRcptNotifyFailure
 func WithDSN() Option {
 	return func(c *Client) error {
-		c.dsn = true
+		c.requestDSN = true
 		c.dsnmrtype = DSNMailReturnFull
 		c.dsnrntype = []string{string(DSNRcptNotifyFailure), string(DSNRcptNotifySuccess)}
 		return nil
@@ -414,7 +417,7 @@ func WithDSNMailReturnType(option DSNMailReturnOption) Option {
 			return ErrInvalidDSNMailReturnOption
 		}
 
-		c.dsn = true
+		c.requestDSN = true
 		c.dsnmrtype = option
 		return nil
 	}
@@ -448,7 +451,7 @@ func WithDSNRcptNotifyType(opts ...DSNRcptNotifyOption) Option {
 			return ErrInvalidDSNRcptNotifyCombination
 		}
 
-		c.dsn = true
+		c.requestDSN = true
 		c.dsnrntype = rcptOpts
 		return nil
 	}
@@ -870,7 +873,7 @@ func (c *Client) sendSingleMsg(message *Msg) error {
 		}
 	}
 
-	if c.dsn {
+	if c.requestDSN {
 		if c.dsnmrtype != "" {
 			c.smtpClient.SetDSNMailReturnOption(string(c.dsnmrtype))
 		}

client_test.go

@@ -483,8 +483,8 @@ func TestWithDSN(t *testing.T) {
 		t.Errorf("failed to create new client: %s", err)
 		return
 	}
-	if !c.dsn {
+	if !c.requestDSN {
-		t.Errorf("WithDSN failed. c.dsn expected to be: %t, got: %t", true, c.dsn)
+		t.Errorf("WithDSN failed. c.requestDSN expected to be: %t, got: %t", true, c.requestDSN)
 	}
 	if c.dsnmrtype != DSNMailReturnFull {
 		t.Errorf("WithDSN failed. c.dsnmrtype expected to be: %s, got: %s", DSNMailReturnFull,