Error in downloading mail on IMAP after ios 18 upgrade

Obi1net: Thanks for the info. Can you clarify the procedure you used? In Mail settings/Advanced I see a greyed-out slash for "IMAP Path Prefix". Is that the one you mean? And what do you mean by typing over it?

Hi George. My apologies for not being clear.

Yes that greyed out slash was the one I meant. By typing over it I meant that I typed a slash to replace the one that was greyed out so that it was black as other text appears when you use the keyboard. It fixed my problem after I did this and rebooted. The exact solution was needed a few days later but so far the fix stuck this time. Sadly I think this is just one symptom of other issues.

That is very discouraging to hear. I run my own Postfix mail server using Dovecot for imap. It has worked fine for many years, but once my iPhone was upgraded to iOS 18, Mailapp would no longer download my email. Like the previous poster, I had made no changes in my server configuration. My other Macs, including my laptop running MacOS Sequoia continue to access email just as before. My Postfix version is 2.11.10 and Dovecot is 2.2.14.

Another detail: Although Mailapp under iOS 18 would not access my email, I could still get it on my phone through webmail (using Roundcube). I'm thinking that narrows down the problem to imap (assuming that Roundcube retrieves mail with some other mechanism.)

I've had to roll back my iPhone to ios 17.6.1.

I am still monitoring this thread and the pain it is causing users. I had the same issue with my iPhone SE using iOS 18.2. After trying a number of suggestions, I found that ensuring I had a backslash after my IMAP server details my Apple mail worked fine. Two days later, no mail was coming through so I checked and found that the IMAP backslash was greyed out again so I typed it in again and rebooted. A week later, my email is still working fine. As a comment, I note that a user has experienced mail issues when using a VPN. I use one on the phone to hotspot to my iPad and laptops and assumed it was still on during this email debacle. I have just checked and saw VPN was off. I again set it to ON and rebooted, only to find it automatically switched itself off. Perhaps that’s why my mail is still working OK with the IMAP backslash in place? For what it is worth, it would appear that iPhone iOS from 18.0 to 18.2 all have the same issue - whatever the cause. Hope this feedback is helpful.

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

Contact Apple Support

Contact - Official Apple Support (CA)

If you ever get them on the phone explain it to the rep, but don't let them put you off. Have it expedited and keep it going until then can either fix while you are on the phone or give you a timeline on when it is going to get fixed.

From what I see in the dovecot documentations, it will use "." as a separator if none is defined.

namespace/separator

• Default: ‘.’ for Maildir; ‘/’ for other mbox formats
• Values: String

Specifies the hierarchy separator for the namespace.

The separator is a single character, which can’t then otherwise be used in folder names.

The commonly used separators are . and /, but other separators can be used as well. For example ^ is less likely to be found in normal folder names.

Recommended value is to leave it empty and accept the default value.

Example:

namespace {
  separator = /
}

See also

Hierarchy Separators

From dovecot.org

The same…. I can’t understand why this issue is still not resolved by apple….

same issue here. Very slow response

from Apple

Me too. And how do I fix it when I cannot access internet? Over to you Apple. If no quick fix, I fear you will lose very many customers. Your lack of response and lack of a fix is unacceptable.

Hi all,

I have the same problem (Network error POSIX 96). The emails do not download and refresh correctly through the native Mail app. Sometimes, they do download but I am unable to open the content of the email. I have contacted the local provider of my email and I have been informed that the issue is on Apple side. When will this be fixed? This is a serious issue. :(

There are 2 error i have notice in my dovecot setup while my iPhone Mail app given POSIX 96 error.

First time dovecot given the error "imap-postlogin: Error: ERROR 145 (HY000) at line 1: Table './last_login/lastauth' is marked as crashed and should be repaired", that is have fixed by repairing that table in mysql.

Second time dovecot given the error "imap(......@..........in): Error: mmap() failed with file /var/vmail/vmail1/..../Maildir/dovecot.index.cache: Cannot allocate memory". For this error i have increased default_vsz_limit from 256M to 512M.

Overall My Understanding is Dovecot having any error in it plugin apart from IMAP protocol, other clients are ignoring it, where us the latest Mail app throwing the error in client side. So blaming iOS18 or new Mail app is not good.

May be i can help you to fix if you share the truncated logs while accessing Mail app to your server.