feat(mailer): brand account access emails

Assisted-by: Codex:GPT-5

services/mailer/mail_user.go

@@ -34,6 +34,7 @@ func sendUserMail(language string, u *user_model.User, tpl templates.TplName, co
 		"Code":              code,
 		"Language":          locale.Language(),
 	}
+	subject = renderUserMailSubject(tpl, data, subject)
 
 	var content bytes.Buffer
 
@@ -48,6 +49,18 @@ func sendUserMail(language string, u *user_model.User, tpl templates.TplName, co
 	SendAsync(msg)
 }
 
+func renderUserMailSubject(tpl templates.TplName, data any, fallback string) string {
+	var subject bytes.Buffer
+	if err := LoadedTemplates().SubjectTemplates.ExecuteTemplate(&subject, string(tpl), data); err != nil {
+		log.Error("ExecuteTemplate [%s]: %v", tpl+"/subject", err)
+		return fallback
+	}
+	if rendered := sanitizeSubject(subject.String()); rendered != "" {
+		return rendered
+	}
+	return fallback
+}
+
 // SendActivateAccountMail sends an activation mail to the user (new user registration)
 func SendActivateAccountMail(locale translation.Locale, u *user_model.User) {
 	if setting.MailService == nil {
@@ -119,6 +132,7 @@ func SendRegisterNotifyMail(u *user_model.User) {
 		opts := &user_model.TimeLimitCodeOptions{Purpose: user_model.TimeLimitCodeResetPassword}
 		data["Code"] = user_model.GenerateUserTimeLimitCode(opts, u)
 	}
+	subject := renderUserMailSubject(mailAuthRegisterNotify, data, locale.TrString("mail.register_notify", setting.AppName))
 
 	var content bytes.Buffer
 
@@ -127,7 +141,7 @@ func SendRegisterNotifyMail(u *user_model.User) {
 		return
 	}
 
-	msg := sender_service.NewMessage(u.EmailTo(), locale.TrString("mail.register_notify", setting.AppName), content.String())
+	msg := sender_service.NewMessage(u.EmailTo(), subject, content.String())
 	msg.Info = fmt.Sprintf("UID: %d, registration notify", u.ID)
 
 	SendAsync(msg)