I’m experiencing issues with receiving emails on my Mailcow setup. While I can send emails without any problems, receiving them is a challenge. Currently, only mailboxes within the same domain can exchange emails. External sources, like Gmail, can’t send emails to my setup.
It’s worth noting that my ISP has imposed significant traffic restrictions. Both SMTP and SMTPS are blocked, and they’ve refused to make exceptions. However, both IMAP and IMAPS are active, accessible from external sources, and are not blocked by the ISP. As a result, I’m unable to modify my rDNS record, though I’m not sure if that’s relevant to my current issue.
The only port I’ve been permitted to use is the SUBMISSION port (587). I’ve attempted to diagnose the issue using custom Python scripts to send emails from external sources. However, in every case, the Mail Delivery System reports a failure in sending the email.
Any insights or solutions would be greatly appreciated. Thank you!