Apple.mail - cannot reliable connect to IMAP server.

Question

Level 1

133 points

Apple.mail - cannot reliable connect to IMAP server.

I have a 2020 iMac, 500 GB SSD, 27” monitor, macOS 26.0.1

Multiple times a day I having a problems with mail not sending from the Mail.app because of a failure to connect to the SMTP and/or iMAP serverS. This can be confirmed by going to Mail > Window >Connection doctor and see both the IMAP and SMTP trying, but failing to connect. What works for me once was going to Mail > Settings > Accounts > iCloud Account > Server Settings > Outgoing Mail Account >finding that [iCloud Offline] was selected. I clicked on [iCloud] and that solved the problem.

However, this has happened several times a day since then and when I follow the same path, [iCloud Offline] is not there. Only iCloud is there and it is selected.

Restarting the computer usually fixes it but then, later, I'll go back to Mail again to find I am disconnected and need to restart to re-establish the connection to the IMAP server.

Help! Please???

iMac 27″, macOS 26.0

Posted on Oct 23, 2025 10:53 AM

Reply

Answer 1

AlWeir

Level 5

4,983 points

Oct 23, 2025 11:06 AM in response to Room101A

If you are using a VPN or a proxy or you are running a 3rd party Firewall and or a Anti Virus piece of software it could be hampering your Mac

Reply

Answer 2

AlWeir

Level 5

4,983 points

Oct 24, 2025 8:00 AM in response to Room101A

I would then check with support at Synology and see if they might have a update to their router for this particular problem. It could be the VPN that is causing the problem that runs with the router.

Reply

Answer 3

Room101A Author

Level 1

133 points

Oct 23, 2025 6:47 PM in response to AlWeir

Thanks for responding and the answer to all you questions is an emphatic NO! Since my Synology Router has a firewall I see no need even to turn on the Apple firewall on my iMac. Moreover, Mail has happily co-existed with that router firewall sending and receiving mail over multiple Mail.app accounts for over five years.

I wonder if the Tahoe "version" or Mail.app plays nicely when deployed on an Intel Mac.

And thank you again for taking the time to respond; kind of you to do so and I upvoted your response.

Reply

Answer 4

Room101A Author

Level 1

133 points

Oct 24, 2025 9:11 AM in response to Room101A

Good point. I'll do that. Meantime, I restarted in Recovery Mode and ran FirstAid on the Macintosh SSD: passed.

Since I was in Recovery Mode, I thought "What the hey" and reinstalled Tahoe.

In the hope that some setting in the following might need to be changed I offer this:

When all was done and I opened Mail for the first time, I went to Mail > Settings > Accounts > iCloud > Server settings to see how they were configured. They were as follows:

Outgoing Mail Server [None]

When I clicked on the Pop-up? for Outgoing Mail Server, there were my emails addresses for the following accounts:

AOL

Gmail

iCloud

iCloud (Offline)

Yahoo

GMX

...and none of these were selected.

[Edit SMTP Server List...] showed these settings:

iCloud.... imap.mail.me.com

my GMX address....mail.gmx.com

Below under [Server Settings] was

Description: iCloud

User Name: My icloud email account

Password: ••••••etc.

Host Name: imap.mail.me.com

And [Automatically manage connection settings] was checked.

Off to check for a Synology update.

Reply