Dumb question: how can I test emails from freePBX?

postfix is set up and sending fine from command line.

How can I test that freePBX can send?

Implementation team used to test Voicemail-to-email as part of QA Tests

FreePBX GUI > Admin > SysAdmin Pro > Email Setup > Debug

In paid version only I presume?

Yes, reply edited. There is a one month free trial of SysAdmin Pro in the Sangoma Portal store:

Test by sending from the CLI
[root@freepbx ~]# sudo -u asterisk mail -s TestEmail [email protected]
CTRL+D, Enter