OK, so I have mutt receiving emails fine, but I'm having issues sending them. When I first went to test mutt's sending of emails today, I couldn't get any emails to send as the error message returned was "invalid SMTP URL". It took me about an hour before I discovered I had written "smpts://" in the config file (*facepalm*).
As a result of changing this, one account works fine, but the other is giving SASL authentication errors. I made sure that emails sent fine with the same settings from my smartphone and they did, but I can't track it down here for some reason? I'm using the latest version of Cyrus-SASL v2.
If anyone has any ideas and I haven't posted an update, send me a message on the fediverse at @ddlyh@topspicy.social.
I figured it out! I just had to put the smtp_url in double speechmarks instead of single ones!