Fix in address handling and more header related methods

Author: Winni Neessen

header.go

@@ -20,6 +20,9 @@ const (
 	// HeaderContentLang is the "Content-Language" header
 	HeaderContentLang Header = "Content-Language"
 
+	// HeaderContentLocation is the "Content-Location" header (RFC 2110)
+	HeaderContentLocation Header = "Content-Location"
+
 	// HeaderContentTransferEnc is the "Content-Transfer-Encoding" header
 	HeaderContentTransferEnc Header = "Content-Transfer-Encoding"
 
@@ -50,6 +53,9 @@ const (
 	// See: https://datatracker.ietf.org/doc/html/rfc2045#section-4
 	HeaderMIMEVersion Header = "MIME-Version"
 
+	// HeaderOrganization is the "Organization" header field
+	HeaderOrganization Header = "Organization"
+
 	// HeaderPrecedence is the "Precedence" header field
 	HeaderPrecedence Header = "Precedence"
 
@@ -62,6 +68,12 @@ const (
 	// HeaderSubject is the "Subject" header field
 	HeaderSubject Header = "Subject"
 
+	// HeaderUserAgent is the "User-Agent" header field
+	HeaderUserAgent Header = "User-Agent"
+
+	// HeaderXMailer is the "X-Mailer" header field
+	HeaderXMailer Header = "X-Mailer"
+
 	// HeaderXMSMailPriority is the "X-MSMail-Priority" header field
 	HeaderXMSMailPriority Header = "X-MSMail-Priority"
 

msg.go

@@ -151,7 +151,7 @@ func (m *Msg) SetHeader(h Header, v ...string) {
 func (m *Msg) SetAddrHeader(h AddrHeader, v ...string) error {
 	var al []*mail.Address
 	for _, av := range v {
-		a, err := mail.ParseAddress(m.encodeString(av))
+		a, err := mail.ParseAddress(av)
 		if err != nil {
 			return fmt.Errorf("failed to parse mail address header %q: %w", av, err)
 		}
@@ -337,6 +337,17 @@ func (m *Msg) SetImportance(i Importance) {
 	m.SetHeader(HeaderXMSMailPriority, i.NumString())
 }
 
+// SetOrganization sets the provided string as Organization header for the Msg
+func (m *Msg) SetOrganization(o string) {
+	m.SetHeader(HeaderOrganization, o)
+}
+
+// SetUserAgent sets the User-Agent/X-Mailer header for the Msg
+func (m *Msg) SetUserAgent(a string) {
+	m.SetHeader(HeaderUserAgent, a)
+	m.SetHeader(HeaderXMailer, a)
+}
+
 // GetSender returns the currently set FROM address. If f is true, it will return the full
 // address string including the address name, if set
 func (m *Msg) GetSender(ff bool) (string, error) {