Error in downloading mail on IMAP after ios 18 upgrade

If you’re getting mail error POSIX 96 after updating to ios18 then try turning off VPN.

In my case, I still had the old Hotmail account on the Mail app as my primary email. I got in a live chat with Apple help and they had me delete the Hotmail account and just install Outlook as my primary email. That fixed it; I can now receive/send email using my original hotmail address through outlook. I hope this helps someone—sorry I’m not more tech savvy.

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 have this issue on an email account provided by an ISP. This is what their community manager had to say when I posted about it on their forums:

"So the best thing to do is remove the entire mailbox and then try recreating and authenticating. If it still does not work we have noticed that Port 143 is being used as a side port but it is not secured and cannot be accessed off network. We are working on trying to further address the issue. For now, have use the Webmail."

Obviously, I've tried removing and re-adding the account multiple times before they even said this, and it doesn't work. What's interesting is that they see port 143 being used as a side port when that isn't specified anywhere in my account settings. Might be some kind of UI bug that is ignoring SSL port numbers and using the default 143 instead, which is causing a conflict as the port isn't allowed in this case.

I understand from what I have read over the past few weeks people that were having problems with POSIX 96 where running VPN's and when they shut them down things started to work again. This doesn't go for everyone.

Saw the forward slash in IMAP field on my phone was greyed out. Backed over it and retyped it. Hit return to move to next field. Backed out of mailbox setup and rebooted. Mail downloaded straight away. Last few days it still works but now cannot see/access any subfolders of account, like bin, sent, junk, etc. However they are all there on my iPad and MacBook.

18.1 update resolved my issue

plinss wrote:

On my test server the only settings defined in the inbox namespace are "separator", and "inbox = yes" , everything else is the default value which should be equivalent to:

namespace inbox {

type = private

separator = "\\"

prefix =

location =

inbox = yes

hidden = no

list = yes

subscriptions = yes

}

This is great to know. As I mentioned earlier my settings are in . . . dovecot/etc/dovecot.conf, and they are minimal with no mention of "namespace inbox." I looked at the Dovecot configuration page you linked to earlier and learned how to use the doveconf and doveadm commands to dump my entire configuration. It is very lengthy presumably listing all the many defaults. When I search it for "namespace" nothing appears but I do have these settings in the output, both blank:

auth_master_user_separator =

master_user_separator =

If I understand correctly that probably means Dovecot is using the backslash separator (\) as a default. So maybe I'll try adding the stanza from your config with the backslash escaped (\\) and see what happens. Then try a forward slash (/) instead. Right now I'm still back on ios 17.x until I work up the nerve to upgrade and try the fix.

FINALLY.. gmail on my iPhone with 18.1.1 iOS is working for me!!

I did the following:

1. Shutdown the phone for 10 mins
2. Powered the phone ON and did ‘forget my (home) wifi network
3. Added again my home wifi network
4. Removed my gmail account from the Mail app
5. Added again my Gmail account

And… it started working again!!

I've had this issue since iOS18 and subsequently 18.1 and 18.1.1. All the same messages, POSIX96, POSIX54, Cannot connect, Connecting, mailbox already exists etc.

I believe it's all related the iOS UI handling the mapping of mailboxes. Im no expert at all but after being frustrated again today by missing out on business opportunities because mail just doesn't not come through I did some digging. For the third or fourth time I removed and re-added the email account and realized that the UI doesn't seem to save your changes when mapping the mailboxes under Mail settings > account settings > advanced. Or it might look like it has but has actually done something else. There is no save button and you can only back out of the window. If you go forward again and view your changes they have most likely reverted back to they were or for me on this occasion end up a mix of what I had set.

If you then go over to the mail app and change those settings (why can't they all be in one place Apple?) to match your prefix maps they too do not save and or give some very weird results.

If I view my mailboxes (inbox, sent etc) and click edit top right, then tick all the ones I just mapped in 'account settings > advanced' so they show up and are mapped accordingly nothing sticks or it gives weird results. Previously this (while stupidly overly complex) worked but now it does not. This part too causes crashes, corruption and plain weirdness. If I tick sent mailbox for example I can end up with two! If I click on one of them to view what's in the sent mailbox for example the mailbox can actually be the drafts mailbox not sent! Not all the mailboxes/folder under my IMAP prefix appear, sometimes they do, sometimes they don't. Even when they do all appear and I manage to map everything as it should I still get weird results when actually looking in the mailbox. Sometimes it's empty or it will have items from drafts, or sent in a folder that shouldn't.

I believe it's this that's causing the issue. Mail app and the settings app are broken when it comes to mailbox mapping and so mail app is expecting to receive data from the inbox but it either doesn't (because the link is incorrect despite what the settings say) or gets sent data its not expecting and so we get various error messages. It certainly explains the mailbox already exists messages Ive been getting and possibly POSIX54 server not responding.

Just my experience but I think Apple haven't fixed it yet because they're looking in the wrong place and even when you look in the right place not everything is as it seems.

In case it's helpful, steps to reproduce the error I'm seeing with IMAP accounts. No VPNs or other profiles. Can produce on any network.

1. Kill the Mail app. Allow the automatic Fetch schedule to bring the mailbox up to date in the background. This gets you to a scenario where there is no new email for the Mail app to download.
2. Open the Mail app. This forces a manual Fetch. There is nothing to collect and no error is triggered.
3. Wait for an email to arrive in the affected Mailbox. Perhaps send yourself an email, for example.
4. Force a manual Fetch. The error is triggered. The new email is not downloaded. The Fetch will (eventually) fail. In my particular case it fails with a "POSIX 96" error.
5. No further email will be collected until you kill the mail app and allow the automatic Fetch schedule to bring the mailbox up to date (i.e. return to step 1)

Other email clients, e.g. Outlook, are able to download the mail and continue to operate normally, without the issues described at Step 4 & 5.

Interested to know if this is the same behaviour that others see. Hopefully it helps someone.

We rebooted and the Posix 96 msg stopped, for now

ferrerod wrote:

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

Try this feedback page: Feedback - iPhone - Apple

stephen boyle wrote:

Does anyone else with this issue on dovecot want to test that change? You would need to change the 'imap_capability' configuration parameter in the dovecot conf files. In my case i used imapsync in verbose mode to get the current default advertised capabilities. I then removed 'IDLE' from the string and entered the rest into the configuration file. For example:

imap_capability = IMAP4rev1 LITERAL+ SASL-IR LOGIN-REFERRALS ID ENABLE XAPPLEPUSHSERVICE AUTH=CRAM-MD5 AUTH=PLAIN AUTH=LOGIN

I'd like to give this a try on my server. Would I add the above (or some version of it) to the dovecot.conf file?