Remove USE_DIFFERENT_ENVELOPE_FROM option - instead determine whether to use it from

the value

Signed-off-by: Andrew Thornton <art27@cantab.net>

Author: zeripath

custom/conf/app.example.ini

@@ -1450,8 +1450,7 @@ PATH =
 ;; Mail from address, RFC 5322. This can be just an email address, or the `"Name" <email@example.com>` format
 ;FROM =
 ;;
-;; Sometimes it is helpful to use a different address on the envelope. Set USE_DIFFERENT_ENVELOPE_FROM to true to use ENVELOPE_FROM as the from on the envelope
-;USE_DIFFERENT_ENVELOPE_FROM=false
+;; Sometimes it is helpful to use a different address on the envelope. Set this to use ENVELOPE_FROM as the from on the envelope. Set to `<>` to send an empty address.
 ;ENVELOPE_FROM =
 ;;
 ;; Mailer user name and password

docs/content/doc/advanced/config-cheat-sheet.en-us.md

@@ -598,8 +598,7 @@ Define allowed algorithms and their minimum key length (use -1 to disable a type
   - Otherwise if `IS_TLS_ENABLED=false` and the server supports `STARTTLS` this will be used. Thus if `STARTTLS` is preferred you should set `IS_TLS_ENABLED=false`.
 - `FROM`: **\<empty\>**: Mail from address, RFC 5322. This can be just an email address, or
    the "Name" \<email@example.com\> format.
-- `USE_DIFFERENT_ENVELOPE_FROM`: **false**: Set to **true** to use the value of `ENVELOPE_FROM` as the From address on the SMTP mail envelope.
-- `ENVELOPE_FROM`: **\<empty\>**: Address set as the From address on the SMTP mail envelope if `USE_DIFFERENT_ENVELOPE_FROM` is set to true.
+- `ENVELOPE_FROM`: **\<empty\>**: Address set as the From address on the SMTP mail envelope. Set to `<>` to send an empty address.
 - `USER`: **\<empty\>**: Username of mailing user (usually the sender's e-mail address).
 - `PASSWD`: **\<empty\>**: Password of mailing user.  Use \`your password\` for quoting if you use special characters in the password.
    - Please note: authentication is only supported when the SMTP server communication is encrypted with TLS (this can be via `STARTTLS`) or `HOST=localhost`. See [Email Setup]({{< relref "doc/usage/email-setup.en-us.md" >}}) for more information.

modules/setting/mailer.go

@@ -16,15 +16,15 @@ import (
 // Mailer represents mail service.
 type Mailer struct {
 	// Mailer
-	Name                     string
-	From                     string
-	EnvelopeFrom             string
-	UseDifferentEnvelopeFrom bool
-	FromName                 string
-	FromEmail                string
-	SendAsPlainText          bool
-	MailerType               string
-	SubjectPrefix            string
+	Name                 string
+	From                 string
+	EnvelopeFrom         string
+	OverrideEnvelopeFrom bool `ini:"-"`
+	FromName             string
+	FromEmail            string
+	SendAsPlainText      bool
+	MailerType           string
+	SubjectPrefix        string
 
 	// SMTP sender
 	Host              string
@@ -75,7 +75,6 @@ func newMailService() {
 		SendmailTimeout: sec.Key("SENDMAIL_TIMEOUT").MustDuration(5 * time.Minute),
 	}
 	MailService.From = sec.Key("FROM").MustString(MailService.User)
-	MailService.UseDifferentEnvelopeFrom = sec.Key("USE_DIFFERENT_ENVELOPE_FROM").MustBool()
 	MailService.EnvelopeFrom = sec.Key("ENVELOPE_FROM").MustString("")
 
 	if sec.HasKey("ENABLE_HTML_ALTERNATIVE") {
@@ -97,6 +96,21 @@ func newMailService() {
 	MailService.FromName = parsed.Name
 	MailService.FromEmail = parsed.Address
 
+	switch MailService.EnvelopeFrom {
+	case "":
+		MailService.OverrideEnvelopeFrom = false
+	case "<>":
+		MailService.EnvelopeFrom = ""
+		MailService.OverrideEnvelopeFrom = true
+	default:
+		parsed, err = mail.ParseAddress(MailService.EnvelopeFrom)
+		if err != nil {
+			log.Fatal("Invalid mailer.ENVELOPE_FROM (%s): %v", MailService.EnvelopeFrom, err)
+		}
+		MailService.OverrideEnvelopeFrom = true
+		MailService.EnvelopeFrom = parsed.String()
+	}
+
 	if MailService.MailerType == "" {
 		MailService.MailerType = "smtp"
 	}

services/mailer/mailer.go

@@ -210,7 +210,7 @@ func (s *smtpSender) Send(from string, to []string, msg io.WriterTo) error {
 		}
 	}
 
-	if opts.UseDifferentEnvelopeFrom {
+	if opts.OverrideEnvelopeFrom {
 		if err = client.Mail(opts.EnvelopeFrom); err != nil {
 			return fmt.Errorf("Mail: %v", err)
 		}
@@ -249,7 +249,7 @@ func (s *sendmailSender) Send(from string, to []string, msg io.WriterTo) error {
 	var waitError error
 
 	envelopeFrom := from
-	if setting.MailService.UseDifferentEnvelopeFrom {
+	if setting.MailService.OverrideEnvelopeFrom {
 		envelopeFrom = setting.MailService.EnvelopeFrom
 	}