I should be able to fix it. I had disabled emails completely, but apparently that also disabled emails for signup and reset password. I switched to using outlook as a temp measure, however I think that has a limit of 200 emails per day, which I thought would be fine. However if multiple people are subscribed to a post that gets several relies then you can generate a lot of emails quite quickly.
I think I can set it up so that the emails get sent from our little unix instance, which should alleviate these problems, but it’ll need to figure out how to do it.
The real issue is that Flarum does not deal well with email errors. The fact that the send email fails shouldn’t stop the reply from being posted.