I've been trying to get some friends signed up on my lemmy instance.
The issue is, so far nobody seems to be receiving the signup/verification emails. I am getting the admin user-signup emails, but those are sent to contact@<instance-domain>. I created 2 test users, one with a instance-domain address, and one to a gmail. The instance-domain address was there within a minute, but the gmail one has yet to arrive.
I agree with @terribleplan@lemmy.nrd.li that the inclusion of a postfix SMTP container and using that in the example configs is probably doing more harm than good.
You shouldn't need the Postfix container at all unless you want to manually set that up and know what you're doing. You configure your SMTP settings in the config.hjson file as outlined in the example defaults.hjson file. I'm using a third-party SMTP provider to avoid any deliverability issues with sending emails directly from my server's IP address. Just ensure you configured your DNS correctly (DKIM, etc.), punch in the info, and it should work.