Recurring IMAP connection errors

Yup, having the same issues... pretty annoying

I am having the similar issue but it only happens on my hosters email, iCloud and gmail stay up and running.

Same here. Loosing connection to all my IMAP servers (including iCloud). Restarting Mail helps from time to time, then the connection error is back.

If you haven't restarted the computer, do that first then test.

For iCloud, go to System Preferences and open the iCloud pane. Sign out of iCloud completely, then sign back in. That should clear up issues with it.

For your other accounts, if they are not working, remove the account from internet accounts. Then re-add the accounts back in and test.

I'm not the OP but I have the same problem and have tried both rebooting and resetting all three of my IMAP accounts with no success. Sometimes restarting Mail will cause the IMAP connections to work for awhile but eventually the connections always fail. Since all of my IMAP accounts fail simultaneously, I suspect there is something in El Cap's version of IMAP that causing the problem.

Your problem may be different. If you have different providers and all are still failing, then it may have something to do with your connection. You might want to post a new discussion describing your problem and all you did so far.

I have exactly the same issue - IMAP connections fail. I have 2 Rackspace accounts and 2 Gmail accounts configured with Apple Mail - the problem happens with all 4. After a short period of time I can't make an IMAP connection. I first discovered this because I couldn't put items in the trash. When attempting to trash items there is a small 'Copying Message' displayed in the bottom left corner of Apple Mail. When IMAP connection is working properly this message pops up and goes away very quickly. When IMAP connections are not working this message is displayed for a minute or so before getting an error message that items cannot be moved to the trash and they are returned to the inbox (or whatever box they were in before I attempted to trash them).

It took me a while to figure out that this was only related to IMAP connections, as others have reported I don't have any problem making SMTP connections.

I initially suspected this was related to Apple Mail so I downloaded and installed Air Mail (a very good client, BTW), but I had the same problem. As others have also reported, quitting Apple Mail and restarting fixes the problem temporarily, and so does restarting the computer. I've also discovered that if you switch network connections the problem is also temporarily fixed.

I've tried every combination of settings: changing IMAP ports, SSL/non-SSL, hostnames, IPs, and I've tested on my work network and at home. I've also followed the steps others have posted whereby I've removed accounts, re-installed, I've even set up a brand new account and it has the same problems. It seems the only common component is El Capitan and my MacBook Pro (2015).

This is such a headache for me that I've started managing my mail in the web interfaces for Gmail and Rackspace mail, but I have such a lot of email I'm thinking of rolling back to Yosemite. I'll post an update if I decide to try that.

Anyone else find any other permanent solution rather than rolling back to Yosemite?

Thanks.

I ran across this article from 2014 and the poster said it's still a problem with Mail under El Cap: https://www.inmotionhosting.com/support/email/mac-mail/disable-imap-idle-mac-mai l

After I unchecked the idle setting, I am getting many fewer IMAP failures and the one I do get seem to "cure" themselves within a short period of time without my having to kill and restart Mail. So still not a full solution at this point.

Hope this helps someone else.

Also struggeling with this, but unchecking IDLE seems to help...

After unchecking IDLE I still had AUTOMATIC set for when to check for mail. I sent a couple of emails to myself and noted that it did not check for mail AT ALL unless I clicked the "check mail" button manually. So I changed the setting to EVERY MINUTE and now it seems to work with a max 1 minute delay from when I sent the email. So far so good.