Hello everyone!
This is a followup to my recent post.
I am now happy to announce that our provider (Hetzner - thanks for that!) has unblocked ports required for mail sending. This means that your custom SMTP settings should be working now (but just to make sure, if anyone tests this out, please let me know if it works as intended - if that's not the case, please let me know as soon as possible).
Moreover, SPF, DMARC and DKIM should now all 'PASS'
for all E-mails sent from FreeFlarum - I think this was a thing with the old server too, but I had to re-setup it on the current one. This shouldn't break anything, and it should make E-mails more secure, or more unspoofable at least...