cPanel Emails not being received by some addressees
We are using various cpanel email accounts on our domain. Usually our employees work with Outlook. We experienced some difficulties over the past months and years, when our clients complained that they didn't receive our emails. We, on the other hand, did not get any notification that outgoing emails haven't been delivered.
Now we carried out some tests with the help of some of our clients that would sometimes not receive emails from us in the past. We found out that emails from an email account set up in Outlook with SSL (n1plcpnl0047.prod.ams1.secureserver.net) are not being received, while emails from the same account set up in Outlook using Non-SSL Settings are being received.
We repeated the test on Android devices using BlueMail with the same result. Emails sent over secureserver are not being received while emails sent over mail.ourdomain.com are being received.
We verified all Outlook accounts settings (either SSL or non-SSL) and are positive that all of them are set up correctly. Normally our clients are receiving our mails, mentioned problem "only" applies to about 5% of our clients.
The instant solution now would be to set up all Outlook accounts using non-SSL settings. But I really dont want to call that the final solution, even Godaddy describes non-SSL settings as "NOT Recommended"
Anyone here experiencing a similar problem or having an idea how to solve this issue?