Error in downloading mail on IMAP after ios 18 upgrade

plinss wrote:

Interesting, thanks for that. It seems the we're either facing different issues, or there are other configuration settings that impact this. Do note that the excerpt you quoted above seems to be for shared mailboxes, you may have a different configuration for your inbox. Look for a namespace that contains "inbox = yes".

…

Here's what looks like the germane section of that excerpt:

namespace inbox {
  # Namespace type: private, shared or public
  #type = private

  # Hierarchy separator to use. You should use the same separator for all
  # namespaces or some clients get confused. '/' is usually a good one.
  # The default however depends on the underlying mail storage format.
  #separator = 

  # Prefix required to access this namespace. This needs to be different for
  # all namespaces. For example "Public/".
  #prefix = 

  # Physical location of the mailbox. This is in same format as
  # mail_location, which is also the default for it.
  #location =

  # There can be only one INBOX, and this setting defines which namespace
  # has it.
  inbox = yes
…
}

These are all default settings. Never touched them. Always worked, and still work on everything but iOS 18.x.

Another thing I found during my testing is that I can change the separator to something other than "\\", restart Dovecot, connect my iPhone to that account, then change it back to "\\" and restart dovecot again and the iPhone keeps working. It just needed to get past the initial handshake (and likely the LIST command). If I restart Mail, then it once again fails to connect.

Got the same issue, upgrade done (18.1.1). Issue gone. But problem still exists.. when I am in Low Power Mode -> cannot receive messages, POSIX 96 error (via IMAP).

in normal mode, everything is okey

I believe the information shared to date can be concisely summarized as follows:

• iOS 18 has a serious bug in the mail app, that renders IMAP unusable for many users;
• the bug has not yet been fixed in 18.1.1;
• Apple may or may not have acknowledged the bug. One user reported he was told Apple has identified a possible fix. I hope.
• There are a number of workarounds that some people have had some success with. These are not fixes, however, but bandaids. I believe that some people who have reported that one thing or another solved the problem under discussion may have simply eliminated or limited a normally innocuous condition that should not choke a mail client, but which iOS 18 can't handle;
• It is not helpful to complain to the readers of this thread. Here's where you can complain to Apple and report bugs: Feedback - iPhone - Apple

Apple Engineers and Product Managers do not look at the discussions.apple.com

Please either call Apple Support and have your case added to the "existing case": 1-800-MY-APPLE

Unfortunately there is currently NO Feedback for iOS/iPadOS Mail on this page. Only for macOS. I suggest you file a Bug Report anyway, and just add iOS/iPadOS 18.x in the Subject!

Feedback for Mail: Feedback - Mail - Apple

Ensure you select Feedback Type: Bug Report

I have 3 accounts, all IMAP, all on the same server. I verified the iOS 18 Account settings are identical for all 3. The ONLY difference between the 3 accounts is the username, password, and number of messages, and folder structure of one account.

Two accounts work flawlessness under iOS 18 (though I cannot recall if this was always true).

The one account (my primary of course) that does not work has two notable differences from the other two:

1. It is significantly larger in number of messages and size of Inbox.
2. It contains sub folders to organize messages.

One of the two working accounts says it has ~1000 messages, the other has several hundred.

The one that is failing has 12,528 messages in Inbox (1.42 GB), and Sent has 27,474 (2.13 GB). Stats on macOS Mail says in total, this account has 107,420 messages (7.22 GB).

I may turn on debug level messages on dovecot and see if anything shows up, but otherwise, it just feels like Mail 18 broke something fundamental when it comes to large mail boxes.

For now just download the AOL app until the fix is applied to the next update. So far, I’m only getting this issue with my AOL email. Both my hotmail and Gmail emails works just fine using the native iPhone mail app.

correct on macOS it would be "/Library/Server/Mail/Config/dovecot/conf.d/20-imap.conf" most likely.

and yes there are many potential negative effects. if your client relies on IDLE (many do for "pushlike" email) this will stop working, effectively setting clients back to having the "fetch" periodically for mail. As the macOS server supports XAPPLEPUSHSERVICE, i am not sure if that still works to notify certain clients via APNS. Also a potential downside would be higher resource utilization on the server.

but as a workaround for now i think i am ok if this gets people into their email again. so far my tests have been positive.

Stephen, how's your testing of removing the advertising of the IMAP IDLE feature going?

I have noted that adjusting my Pihole filtering to stop blocking iCloud Private Relay servers helped substantially - but not completely. Re-enabling the blocking of the servers brings back all the problems. During testing of this I noted that there is likely some interplay with DNS TTL values, which can temporarily make it look like things are fixed when in reality they are not.

I have an open case about this with Apple support; I spoke to my contact person again today and he confirmed that the engineers are aware of the problem and are actively investigating. I've signposted him (again) to this thread. He was keen to point out that they are keen to hear of any fixes, workarounds, etc in support of trying to find ways to reproduce the problem etc. I specifically noted to him the observations made about IDLE and he said he would pass this on.

Fingers remaining crossed for a fix soon.

[Edited by Moderator]

If that fixes your mail, it sounds like you have a different problem. Check your "Private Relay" (PR) settings. That could be in play. Others have commented about PR on this thread. YMMV.

Please don't change it to "\\", that configuration I posted is an example of what doesn't work (for me at least).

Note that as I posted earlier, changing the separator is dangerous. On one of my servers I tested changing from '\' to '/' and while that makes iOS able to connect, it also broke MacOS Mail when dealing with mail in nested folders (it might have sorted itself out if I reset the mail account, but that's not an option for all the other users on my servers).

Also, using `separator = \\` (without the quotes) is not recognized by Dovecot, it treats that as an empty (default) separator. You can check this by running `doveconf -a` to dump all the config settings.

I have a customer with iPads that updated to 18 and now can't see the folders on the IMAP server despite overwriting the greyed '/'.

This is a monumental breakage of a core setup that has been working with the three existing Linux servers for years: CentOS 6.5, CentOS 7, Rocky Linux 8..... all the exact same issue. All running dovecot and sendmail (sendmail is not affected of course).

Trying to redo certificates in dovecot on the servers has made no difference at the server end.

Apple devices persistently show mail.example.com in their setup and not the DNS node name of the Linux servers (based on the last customer screen shot I saw).

One major application used on the iPads only works on the ones they stopped updating to 18, the five that auto-updated are now not working.

Even on Android I seldom use the default e-mail and messaging products and Blue Mail installed on the Apple devices works perfectly, but as the app is specifically wanting to use Apple's e-mail client, this lifeline is/was short-lived.

I see this update issue has been on the go since September-ish - how on earth has such a monumental breakage in functionality clearly on the Apple device end persisted to not work for months now?

Today I am looking at running up a Rocky Linux 9 VM as the customer is desperate to try 'anything' to fix this, but I hold out little hope this issue can be fixed on the Linux end as none of the others work.

This now will lead to a huge swing away from Apple if something 18.x update does not undo what has been broken.

My problem was that my iPhone only connected to my WiFi when it wanted to. My error message was POSIX50. I also had to reboot WiFi for TVs multiple times. On Dec 2 I lost all Verizon service. The Verizon technician found that mice had infested the outside box. The box was replaced, and my phone now connects to WiFi every time now.

This is likely not the cause of most folks problems, but it could be worth checking out.

stephen boyle wrote:

what OS are you running dovecot on? that would help point in the correct directon

The server is on El Capitan 10.11.6. My mail server is Postfix 3.2.2 with Dovecot 2.3.16. Telnet to localhost 143 reports: * OK [CAPABILITY IMAP4rev1 LITERAL+ SASL-IR LOGIN-REFERRALS ID ENABLE IDLE STARTTLS AUTH=PLAIN AUTH=LOGIN] Dovecot ready.

I use the Outlook.com option on iOS Mail for Hotmail and Outlook emails. Others have switched to the Outlook app from the app store to get around the Mail snafu on both iOS and ipados.