@scooke Solution was deleting a buch of files from path:
/home/yellowtent/boxdata/mail/haraka-queue
that files were created past Jan-06.
On that day we had an account hijacked that started sending out spam. I deactivated the account and it was working fine until past feb-16th, when email service started to crash.
HTH.
@rfg You have to setup a mail relay for your outbound mails. The big cloud providers like aws, gce, azure will all block emails from VMs directly. See https://cloudron.io/documentation/email/#relay-outbound-mails
@rfg This was a bug in our previous version. You can fix this by going to services -> mail -> restart. You have to do this only once, future certificates will be setup correctly.