From 8987f0890a7d181f98f870c59310a081013ffeac Mon Sep 17 00:00:00 2001
From: kolaente <k@knt.li>
Date: Thu, 8 Jan 2026 15:51:31 +0100
Subject: [PATCH] fix(mail): disable queue when mailer disabled (#2069)

- Don't create the mail queue when the mailer is disabled to prevent
`SendMail()` from blocking indefinitely
- Add guard clause in `SendMail()` to return early when mailer is
disabled or queue is nil
- Add test to verify notifications don't block when mailer is disabled

This implements the changes from #1080 with the review feedback
addressed (using `package notifications` instead of `package
notifications_test`).


Closes #1080
---
 pkg/mail/mail.go                          |  5 +-
 pkg/mail/send_mail.go                     |  4 ++
 pkg/notifications/notify_disabled_test.go | 59 +++++++++++++++++++++++
 3 files changed, 66 insertions(+), 2 deletions(-)
 create mode 100644 pkg/notifications/notify_disabled_test.go

diff --git a/pkg/mail/mail.go b/pkg/mail/mail.go
index 21715a6e6..2cc9e50f5 100644
--- a/pkg/mail/mail.go
+++ b/pkg/mail/mail.go
@@ -84,12 +84,13 @@ func getClient() (*mail.Client, error) {
 
 // StartMailDaemon starts the mail daemon
 func StartMailDaemon() {
-	Queue = make(chan *mail.Msg, config.MailerQueuelength.GetInt())
-
 	if !config.MailerEnabled.GetBool() {
+		Queue = nil
 		return
 	}
 
+	Queue = make(chan *mail.Msg, config.MailerQueuelength.GetInt())
+
 	if config.MailerHost.GetString() == "" {
 		log.Warning("Mailer seems to be not configured! Please see the config docs for more details.")
 		return
diff --git a/pkg/mail/send_mail.go b/pkg/mail/send_mail.go
index 57e02c1d6..c19bdd81f 100644
--- a/pkg/mail/send_mail.go
+++ b/pkg/mail/send_mail.go
@@ -128,6 +128,10 @@ func SendMail(opts *Opts) {
 		return
 	}
 
+	if !config.MailerEnabled.GetBool() || Queue == nil {
+		return
+	}
+
 	m := getMessage(opts)
 	Queue <- m
 }
diff --git a/pkg/notifications/notify_disabled_test.go b/pkg/notifications/notify_disabled_test.go
new file mode 100644
index 000000000..55b950c6a
--- /dev/null
+++ b/pkg/notifications/notify_disabled_test.go
@@ -0,0 +1,59 @@
+// Vikunja is a to-do list application to facilitate your life.
+// Copyright 2018-present Vikunja and contributors. All rights reserved.
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+package notifications
+
+import (
+	"testing"
+	"time"
+
+	"code.vikunja.io/api/pkg/config"
+	"code.vikunja.io/api/pkg/i18n"
+)
+
+type disabledMailNotifiable struct{}
+
+func (d *disabledMailNotifiable) RouteForMail() (string, error) { return "test@example.com", nil }
+func (d *disabledMailNotifiable) RouteForDB() int64             { return 1 }
+func (d *disabledMailNotifiable) ShouldNotify() (bool, error)   { return true, nil }
+func (d *disabledMailNotifiable) Lang() string                  { return "en" }
+
+type disabledMailNotification struct{}
+
+func (n *disabledMailNotification) ToMail(string) *Mail {
+	return NewMail().Subject("Test").Line("Test")
+}
+func (n *disabledMailNotification) ToDB() any    { return nil }
+func (n *disabledMailNotification) Name() string { return "disabled.mail.notification" }
+
+func TestNotifyDoesNotBlockWhenMailerDisabled(t *testing.T) {
+	config.InitDefaultConfig()
+	config.MailerEnabled.Set(false)
+	i18n.Init()
+
+	done := make(chan struct{})
+	go func() {
+		_ = Notify(&disabledMailNotifiable{}, &disabledMailNotification{})
+		close(done)
+	}()
+
+	select {
+	case <-done:
+		// Success - Notify returned without blocking
+	case <-time.After(1 * time.Second):
+		t.Fatal("Notify blocked when mailer was disabled")
+	}
+}