iOS 18 and IMAP, my findings but no solution

We had the same problem with our dovecot server in the last days. In our case the problem was in a broken file in the home of the user ( where the mail folders are stored ). The filename had a newline char in. That file was there from 2002 so something has changed in the ios client. I suppose that some imap errors are now fatal for ios mail.

iOS/iPadOS 18.2 seems to have resolved these issues for me. The devices are once again pushing messages to the IMAP server as they should.

What I have found is that SOME accounts still work on IOS 18 mail. Accounts that do work (meaning that it will pull down new mail messages) are accounts where the total mailbox is less than 1.7GB (13,912 messages), with the inbox having a size of 1.5GB (12,432 messages). On the SAME mail server, another account, that has a total mailbox size of 7.49GB (102,852 messages), with an inbox size of 4.44GB (70,797 messages) does NOT WORK.

I have another example where a mailbox size of 15.18GB (132,204 messages), with an inbox size of 15.1 MEGABYTES (only 54 messages!!!) that also DOES NOT WORK. this account does have countless subfolders beneath the inbox for filing message.

While I thought originally it was something to do with inbox size or message total, clearly, the issue is more complex than that. I am trying to narrow down the statistics between accounts that do work vs those that do not, so that we can Apple to recognize (and ultimately fix) this issue.

There’s definitely something up with iOS and iPadOS 18 where third-party IMAP is concerned. I have a situation like yours, where an account that was previously working perfectly no longer works with the default Mail app, but works with other clients apps. Another account on the same server mostly works, except that the Mail app won’t push sent messages to the server-side Sent Messages folder. I’ve filed a bug report with Apple, no response yet.

vicim wrote:

My temporary solution for the moment is to install Outlook on the units with problems that works.

That is now my permanent solution, fixes a lot of problems, except where older devices are not supported by Outlook app (eg iOS15 no longer supported)

When AI starts to play with my mail I don't want to be anywhere near Mail app.

Report it https://apple.com/feedback

Meanwhile change the password in Safari in the web version of your email account (Never use Mail or settings to change email passwords)

Bug report at https://apple.com/feedback

as I said earlier.

This is not the Apple complaints department.

This is NOT a true statement (at least with every provider I have ever worked with, and I believe that I have worked with MOST). That being said, these same accounts, with the same storage considerations worked just fine on EVERY version of IOS pror to 18. AND, because I can demonstrate with at least one account with only 54 messages in the inbox NOT WORKING, your recommendation has no application here.

LD150, links to documentation (dovecot or otherwise) supporting your claim that high inbox message counts “will break many provider systems” would be more helpful than ad hominem attacks on those whose email filtering technique differs from yours. “Inbox should be empty?” Good grief.

I've been managing mailservers for 30 years. The size & message count of an IMAP inbox has no bearing on OP's issue, and only affects performance insofar as personal internet bandwidth or server storage space are concerned -- there are no set limits on message count or overall mailbox size in dovecot, except what the server administrator assigns in the way of quotas. Subfolders can be a convenience but are not necessary; the wonders of indexed plain-text searching, message threading, etc. allow the IMAP inbox to be used as the tool it actually is: a big data bucket, a search engine for your email communication history. You're still thinking about your inbox the same way you did 20 years ago...but things have changed.

For me, the 18.2 has NOT fixed anything with MAIL. Still, the smaller accounts on my phone work, the LARGER ones DO NOT. I have confirmed that these larger mail accounts DO WORK with OUTLOOK. Shame on Apple for making me resort (even temporarily) to that Microsoft Abomination. Assuming that these mail issues with large accounts stem from the new "mail sorting features", I wish Apple would allow the users to choose whether or not to use them.

Again, these same accounts that DO NOT WORK on IOS 18.x mail, still work fine on iPhones running 17.x.

I'm still seeing odd issues with the iOS/iPadOS Mail app not pushing messages to the IMAP server properly, so mail is getting lost in the ether...but I have discovered one bit of evidence that might help some people. It lines up with some of what jamesfrommichigan city has found, and will doubtless bring a wry smile to LD150's face. My wife is notorious (in our household) for her lack of inbox maintenance. She had >10k messages in her inbox, about 2k unread, and her iPhone and iPad stopped updating their respective inboxes. Once I got the total count below 10k, her iOS/iPadOS Mail apps once again showed the proper inbox content. Message size doesn't seem to matter in this case AFAICT, just overall count being above 10k.

Inbox should he empty. Leaving that amount of mail in the Inbox will break many provider systems.

Use folders.

The advice is however valid regarding your ridiculous 102,000 inbox messages. I thought people learned not to do that 20 years ago.

Hey Charlie Brown, it's not a claim, its years of experience.