** How to configure firewall to receive email messages **

Hi @Kristo ,

Yes, you have to configure a mail server for Email alert.  

Please check this KB:

Technical Tip: Use FortiGate automation stitches for alert emails

https://community.fortinet.com/t5/FortiGate/Technical-Tip-Use-FortiGate-automation-stitches-for-alert-emails/ta-p/193355

By default, it should be pointing to FTGD SMTP server, which should work fine. At least it's working for my home 40F. Sniff at the outgoing port if the SMTP packets are going out.

Toshi

As others have said - yes, you have to configure SMTP server for forwarding alert mails OR, as Toshi mentioned, make sure there is a default by Fortinet mail server System -> Settings. One caveat with using default Fortinet mail servers - they are provided on best effort basis, and work 95% of times, but sometimes, depending on Fortinet side (load etc) may NOT deliver mails at all, or deliver with large delay, like 3-4 hours (happened to me on multiple occasions). 

Anyway, to debug mail sending - enable debug dia debug app alertmail -1  dia deb enable

and try triggering the automation stitch that sends the email.