diff --git a/b64linebreaker.go b/b64linebreaker.go
index ff99696..f471fe5 100644
--- a/b64linebreaker.go
+++ b/b64linebreaker.go
@@ -4,7 +4,13 @@
 
 package mail
 
-import "io"
+import (
+	"fmt"
+	"io"
+)
+
+// ErrNoOutWriter is an error message that should be used if a Base64LineBreaker has no out io.Writer set
+const ErrNoOutWriter = "no io.Writer set for Base64LineBreaker"
 
 // Base64LineBreaker is a io.WriteCloser that writes Base64 encoded data streams
 // with line breaks at a given line length
@@ -19,6 +25,10 @@ var nl = []byte(SingleNewLine)
 // Write writes the data stream and inserts a SingleNewLine when the maximum
 // line length is reached
 func (l *Base64LineBreaker) Write(b []byte) (n int, err error) {
+	if l.out == nil {
+		err = fmt.Errorf(ErrNoOutWriter)
+		return
+	}
 	if l.used+len(b) < MaxBodyLength {
 		copy(l.line[l.used:], b)
 		l.used += len(b)
diff --git a/b64linebreaker_test.go b/b64linebreaker_test.go
index 05c61c3..f2b3891 100644
--- a/b64linebreaker_test.go
+++ b/b64linebreaker_test.go
@@ -7,6 +7,7 @@ package mail
 import (
 	"bytes"
 	"encoding/base64"
+	"fmt"
 	"io"
 	"os"
 	"testing"
@@ -410,6 +411,31 @@ func TestBase64LineBreaker(t *testing.T) {
 	}
 }
 
+// TestBase64LineBreakerFailures tests the cases in which the Base64LineBreaker would fail
+func TestBase64LineBreakerFailures(t *testing.T) {
+	stt := []byte("short")
+	ltt := []byte(logoB64)
+
+	// No output writer defined
+	lb := Base64LineBreaker{}
+	if _, err := lb.Write(stt); err == nil {
+		t.Errorf("writing to Base64LineBreaker with no output io.Writer was supposed to failed, but didn't")
+	}
+	if err := lb.Close(); err != nil {
+		t.Errorf("failed to close Base64LineBreaker: %s", err)
+	}
+
+	// Closed output writer
+	wbuf := errorWriter{}
+	fb := Base64LineBreaker{out: wbuf}
+	if _, err := fb.Write(ltt); err == nil {
+		t.Errorf("writing to Base64LineBreaker with errorWriter was supposed to failed, but didn't")
+	}
+	if err := fb.Close(); err != nil {
+		t.Errorf("failed to close Base64LineBreaker: %s", err)
+	}
+}
+
 // removeNewLines removes any newline characters from the given data
 func removeNewLines(data []byte) []byte {
 	result := make([]byte, len(data))
@@ -425,3 +451,13 @@ func removeNewLines(data []byte) []byte {
 
 	return result[0:n]
 }
+
+type errorWriter struct{}
+
+func (e errorWriter) Write([]byte) (int, error) {
+	return 0, fmt.Errorf("supposed to always fail")
+}
+
+func (e errorWriter) Close() error {
+	return fmt.Errorf("supposed to always fail")
+}
diff --git a/msg_nowin_test.go b/msg_nowin_test.go
index 965b6f3..9eec2eb 100644
--- a/msg_nowin_test.go
+++ b/msg_nowin_test.go
@@ -9,6 +9,7 @@ package mail
 
 import (
 	"context"
+	"os"
 	"testing"
 	"time"
 )
@@ -38,3 +39,19 @@ func TestMsg_WriteToSendmailWithContext(t *testing.T) {
 		})
 	}
 }
+
+// TestMsg_WriteToSendmail will test the output to the local sendmail command
+func TestMsg_WriteToSendmail(t *testing.T) {
+	_, err := os.Stat(SendmailPath)
+	if err != nil {
+		t.Skipf("local sendmail command not found in expected path. Skipping")
+	}
+
+	m := NewMsg()
+	_ = m.From("Toni Tester <tester@example.com>")
+	_ = m.To(TestRcpt)
+	m.SetBodyString(TypeTextPlain, "This is a test")
+	if err := m.WriteToSendmail(); err != nil {
+		t.Errorf("WriteToSendmail failed: %s", err)
+	}
+}
diff --git a/msg_test.go b/msg_test.go
index ed70a73..14178e8 100644
--- a/msg_test.go
+++ b/msg_test.go
@@ -617,7 +617,7 @@ func TestMsg_SetMessageIDWithValue(t *testing.T) {
 	}
 }
 
-// TestMsg_FromFormat tests the FromFormat() method for the Msg object
+// TestMsg_FromFormat tests the FromFormat and EnvelopeFrom methods for the Msg object
 func TestMsg_FromFormat(t *testing.T) {
 	tests := []struct {
 		tname string
@@ -641,6 +641,10 @@ func TestMsg_FromFormat(t *testing.T) {
 				t.Errorf("failed to FromFormat(): %s", err)
 				return
 			}
+			if err := m.EnvelopeFromFormat(tt.name, tt.addr); err != nil && !tt.fail {
+				t.Errorf("failed to EnvelopeFromFormat(): %s", err)
+				return
+			}
 
 			var fa *mail.Address
 			f, ok := m.addrHeader[HeaderFrom]