IMAP timing out in Apple Mail in Big Sur

As others have mentioned, disabling ONLY the EMAIL SHIELD from AVG solved the problem of connectivity to IMAP. So you may want to try this or if you don't have AVG any similar application that may "interfere" with the connections.

Thank you. I already deleted AVG, and there is no other such "thing" on the mac. Again disabled the built-in firewall. What I recognized, that all my folders are "on the server", but there are folders which on my mac includes all the mails, but "on the server" these folders are empty. I tought it seems like before a "specific date" the mails are not synchronized, but after I realized, that there is not such a "rule". So my folders on the "server" are randomly empty. No idea, what to do. Luckily the fresh mails are synchronized.

I have the same problems like many others here. Some Mails (Smtp) are working fine and some not. But i don't have a network filter, there is blocking nothing but is not working also... i'm sure that the Big Sure causes all this problems. With Catalina everything was working fine with the Mails...I'm trying out what i can do.

If your folders on the server side are empty but they contain email on the client side (mac), then this is probably due to a setting of the account to delete fetched email after x days. Yu can change that by right click on the account and then "Edit account...". If you can get new email from the server then it seems it works ok. There is no problem with Big Sur to connect with IMAP, this is a very simple and basic task for Apple to fail. The problem resides always on third party software that is not fully compatible yet with Big Sur. Apple is focusing on security and on keeping even the most tech-ignorant user safe by default and this causes a lot of trouble to software developers which, eventually, they overcome. If one claims he doesn't have third party apps or network filters, then most likely he is not aware of its existence or is not using the native mail app. Of course exceptions do occur, as always.

I lost all my bellsouth.net mail after the upgrade to macOS Big Sur & the patch macOS Big Sur 11.1

As I have Microsoft Office Business Account Paid since it came out. My Outlook Business Mail works, Gmail, iCloud. I called Apple, Microsoft & AT&T.

All my emails worked until the upgrade to macOS Big Sur 11.0.1.

Microsoft Office Business: This is what works!

Excel

Word

Publisher

OneNote

Outlook just sits spins & the dumb message Not Responding.

I still cannot add my bellsouth.net email account. Same error Settings or Password.

This was my backup email since 1999.

All Contacts & emails are gone. Not in iCloud or my Verizon Backup for my 2 iPhones

Brand new MacBook Pro 16” top of the line and 2 new iPhones: iPhone 12 Mini & iPhone 12 Pro Max. It is extremely difficult to understand that Apple is aware and has done nothing to fix the issue. I have been given imap & pop incoming - outgoing smtp settings from AT&T, Apple & Microsoft. And everyone has something different. I still have screenshots from all my Apple devices & have everything written down from the day I said goodbye to Android & Windows to Mac. Now I feel like I am back with Windows. I f there is a wonderful person that can help it would be a beautiful thing.

Stressed by far. Happy Holidays.

I also had problems after upgrading to OS Big Sur from Catalina. Initially a problem as cPanel configurations for domain email accounts did not make a compatible interface for an auto configuration. This appears to have been a cPanel problem. In any event, under Big Sur the Mail app does not take IMAP configurations as in will not save new entries or values, returns to "Automatically manage connection settings", does not offer the settings and protocols that email servers provide such as IMAP4 with port 993 rather than IMAP3 with port 995 and will not connect with an updated password, etc.

Have heard any word when this will be corrected. I lost all my Bellsouth.net email. It's not in my iCloud Backups since I upgraded in November 2020. I truly wish all Microsoft Office Business & Home, etc. software should have been checked since Microsoft was working with Apple & this was on my very new 16" MacBook Pro, 1 day old iPhone Pro Max.

Thank you for your reply. Happy 2021 stay safe and my this new year bring you, your family & friends much happiness.

Same problem with BigSur Mail on my new 2020 iMac. Did anybody come up with a solution other than de-installing anti-virus (and other network filters)? IDK what sucks more. Having to restart router/iMac every time you want to check for new eMails, or having paid for (but being unable to use) network filtering apps?

I feel you pain I lost all my bellsouth email and my paid Microsoft Office Outlook will not open, but all other Office works. It’s really a shame that this was never corrected and I have been dealing with this since the day Big Sur was released in November 2020. Not Beta. I never install Beta anything. Plus my protection is Malwarebytes paid. That Apple told me to get and stop my Norton 360. I have been using my Paid Malwarebytes Premium fir years. All of this happened on the bay day Big Sur was released and it’s all on my new MacBook Pro 16”, iPhone 12 Pro Max, iPhone 12 Mini. So I know your pain. It’s a pain in.....

I'm having the exact same issue in 2021. Was this ever resolved? I have been on the phone for hours with GoDaddy reps and Apple reps, to no avail. Has anyone been able to figure this out or is it time to utilize a new email provider?

Thanks!

Thank you so so very much. Have been tearing my hair out over this for a few weeks now. Turning off the Avast mail shield solved the problem. Hope there is a fix soon to ensure the protection mail shield offers.

Did you try explicitly adding Mail.app to Firewall Options?

Same issue with Xfinity Comcast email.

THIS. I was running AVG virus scanner which Web & Email protection. Switching off the email protection immediately fixed the IMAP connection timeout problem.