Apple Mail shows timeout error for incoming port

Apple Mail showing a timeout error for the incoming mail server on two different MacBooks usually means Mail is having trouble reaching the mail provider’s IMAP/POP server. 

1 - Since it is happening on both an M1 and M2 MacBook, the cause is more likely something shared, such as the network, router, VPN/security software, or the mail provider connection.

2 - Try connecting one MacBook to a different network, such as a phone hotspot. 

3 - If Mail works normally there, the issue is likely with your Wi-Fi network, router, or ISP. 

4 - If the problem continues, check for VPNs, antivirus software, or firewall settings that may be blocking mail connections.

5 - In Apple Mail, go to Mail >> Settings >> Accounts >> Server Settings and confirm the incoming mail server, port number, SSL/TLS setting, and authentication method match your provider’s requirements. Most IMAP accounts use port 993 with SSL/TLS.

6 - You can also check Apple Mail’s connection status by opening Mail >> Window >> Connection Doctor. 

7 - The exact error shown there may help identify whether the issue is a timeout, authentication problem, or server connection failure.

Apple’s troubleshooting guides may also help:

If you can’t send or receive email on Mac

Change Server Settings in Mail on Mac

I am glad the step-by-step information was helpful and gave you something concrete to work with when speaking with your ISP’s tech support.

The fact that their IMAP address is blacklisted is certainly interesting.

It would be helpful to find out why it was blacklisted in the first place, whether it was the result of spam or other suspicious activity originating from their servers, a compromised account, or perhaps an error by the blacklist service itself.

Hopefully, the next technician can determine what caused the listing and get some clarity on whether it has been resolved or is likely to happen again.