diff --git a/docs/setup-guide.rst b/docs/setup-guide.rst
index 61b1559..af102b2 100644
--- a/docs/setup-guide.rst
+++ b/docs/setup-guide.rst
@@ -107,6 +107,9 @@ to ``mail.example.com``.
    set a reverse DNS on your public IP because sent emails would be
    mostly marked as spam. Note that many residential ISP providers
    don't allow you to set a reverse DNS entry.
+   Another option is to use an SMTP-Relay service for outgoing E-Mail
+   to ensure it's not marked as spam, like SMPT2GO, which has a free
+   tier for sending 1000 E-Mails a month.
 
 You can check this with