diff --git a/backend/email.go b/backend/email.go
index 03c6fb9..fc91505 100644
--- a/backend/email.go
+++ b/backend/email.go
@@ -56,6 +56,7 @@ func CreateMailClient() (Mailer, error) {
 
 	client, err := mail.NewClient(
 		"smtp.mailbox.org",
+		mail.WithTLSPortPolicy(mail.TLSMandatory),
 		mail.WithSMTPAuth(mail.SMTPAuthPlain),
 		mail.WithUsername(os.Getenv("EMAIL_USERNAME")),
 		mail.WithPassword(os.Getenv("EMAIL_PASSWORD")),