Mastodon Admin: Troubleshoot Email Delivery
If you are experiencing issues with email delivery for new registration confirmations or other notification emails, here are some things that might help:
Review Logs with...
> sudo journalctl -u mastodon-sidekiq | grep -i smtp
Try sending an email using your mastodon settings on SSMTP (https://linuxhandbook.com/linux-send-email-ssmtp/)
Reach out to your hosting provider and ask whether they are blocking SMTP by default (to prevent email spam)
Search Mastodon Admin forum at https://discourse.joinmastodon.org