diff --git a/sender/sender.go b/sender/sender.go
index db87055c4a5feb4f0f09022c06ff15255bd22662..0a1ac1d6dc711491bd13851cd16724262f4dc3b5 100644
--- a/sender/sender.go
+++ b/sender/sender.go
@@ -13,6 +13,7 @@ import (
 	"mime"
 	"mime/multipart"
 	"mime/quotedprintable"
+	"net/mail"
 	"net/smtp"
 	"net/textproto"
 	"os"
@@ -106,6 +107,21 @@ func smtpHelloHostname() string {
 	return hostname
 }
 
+// extractBareEmail extracts just the email address from a formatted address
+// like "Name <email@example.com>" or returns the input if it's already bare.
+// This is needed for SMTP MAIL FROM command which requires only the email address.
+func extractBareEmail(addr string) string {
+	if addr == "" {
+		return ""
+	}
+	parsed, err := mail.ParseAddress(addr)
+	if err != nil {
+		// If parsing fails, return as-is (it might already be bare)
+		return addr
+	}
+	return parsed.Address
+}
+
 // generateMessageID creates a unique Message-ID header.
 func generateMessageID(from string) string {
 	buf := make([]byte, 16)
@@ -742,7 +758,7 @@ func SendEmail(account *config.Account, to, cc, bcc []string, subject, plainBody
 	}
 
 	// Send Envelope
-	if err = c.Mail(account.GetSendAsEmail()); err != nil {
+	if err = c.Mail(extractBareEmail(account.GetSendAsEmail())); err != nil {
 		return nil, err
 	}
 	for _, r := range allRecipients {
@@ -954,7 +970,7 @@ func SendCalendarReply(account *config.Account, to []string, subject, plainBody
 		}
 	}
 
-	if err = c.Mail(account.GetSendAsEmail()); err != nil {
+	if err = c.Mail(extractBareEmail(account.GetSendAsEmail())); err != nil {
 		return nil, err
 	}
 	for _, r := range to {
diff --git a/sender/sender_test.go b/sender/sender_test.go
index d6a0efb8db48baca5d323d489bd502495fb8aefe..a323db2474a044274bbf23e110a417381835b12c 100644
--- a/sender/sender_test.go
+++ b/sender/sender_test.go
@@ -130,3 +130,46 @@ func TestGenerateMessageID(t *testing.T) {
 		t.Errorf("Message-ID has an empty random part, got %s", msgID)
 	}
 }
+
+func TestExtractBareEmail(t *testing.T) {
+	tests := []struct {
+		name     string
+		input    string
+		expected string
+	}{
+		{
+			name:     "bare email",
+			input:    "user@example.com",
+			expected: "user@example.com",
+		},
+		{
+			name:     "formatted with name",
+			input:    "John Doe <user@example.com>",
+			expected: "user@example.com",
+		},
+		{
+			name:     "formatted with quoted name",
+			input:    "\"John Doe\" <user@example.com>",
+			expected: "user@example.com",
+		},
+		{
+			name:     "empty string",
+			input:    "",
+			expected: "",
+		},
+		{
+			name:     "invalid format returns as-is",
+			input:    "not-an-email",
+			expected: "not-an-email",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := extractBareEmail(tt.input)
+			if got != tt.expected {
+				t.Errorf("extractBareEmail(%q) = %q, want %q", tt.input, got, tt.expected)
+			}
+		})
+	}
+}