Error in downloading mail on IMAP after ios 18 upgrade

To resolve this issue do this:

Go to settings - mail app - open the mail account you have problem with - incoming settings - IMAP Path Prefix — replace the greyed out / with a \ instead.

save = problem solved.

As per my understanding POSIX 96 error is related to your server side error. Also based on your issue explanation, your mail server might be having session handling/holding issues. Check your IMAP/POP3 server error log or run your IMAP/POP3 server in debug mode to get more information.

hi - just talked to Naisha in apple support. after much troubleshooting she had me delete the VPN App i had on my phone and mail started working normally.

try that if you have a VPN app on your phone.

I was having the same issue all day on the Mail iOS app with both of my Gmail accounts. I then realized I was connected to a VPN on my phone so I disconnected it and it immediately fixed the email issues!

Thanks to whom ever said turn off vpn. Forgot it was running and that was the reason.

The Posix issue in my case was related to my password. The moment I removed the special characters from the password my mail started coming in. This is what needs to be fixed in the mail app. I do not have this issue uding Microsoft Outlook

...i've found a workaround for the syncing issue: Switch off wifi on the iPhone and use the mobile network.

The problem could be related to the fact that i use a static ip and my own domain name for the home network. However, the mail problem also occurred with SMTP mail accounts that do not use my domain name. I have no problems receiving mail with my Macs, I just noticed that when I tried to set up an account in Thunderbird on the Mac, I got a certificate warning that I had to manually override. Other than that, I have no problems with other web services on the iPhone or any other devices.

However, switching off Wifi on the iPhone and using the mobile network now at least allows me to receive mail again with the Mail.app on iOS 18.2, even with mail accounts that use my domain but are hosted externally by a service provider.

I just migrated an iOS 18.2 iPhone to my self hosted postfix/dovecot setup and it was having problems getting mail with IMAP. It would say "downloading" and do nothing. It would not sync folders. I tried changing dovecot namespace separators, capability strings, etc. Nothing helped. I disabled pihole on my LAN - no change. If I moved the phone to the mobile connection it worked correctly. I removed all SSIDs on the local wifi network and re-signed in to one of them. Since reconnecting to wifi, mai lis working correctly. I have no idea why, but that is what it is doing.

The Mail app continues to work on IOS 18.2 without special characters in the password, but fails to work if password contains special characters

This may not be the Mail App issue, When i got new iPhone with iOS18, i got the same issue after the migration and even i deleted the account and recreated in Mail app, it did not worked. Then i have checked my server about the dovecot error log and i noticed that its had issue in keeping the authentication session and i fixed it, then Mail app started getting message and its not showed any error related to POSIX 96 till now.

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.

Hi Playpossum. I went through the usual steps to get to the account/advanced setting and in IMAP Path Prefix I noted the forward slash was greyed out. I tapped to put the cursor in the field, backspaced over the greyed forward slash and typed over it, changing the forward slash to black. Tapped Return to move out of the field and then backed out of the mail settings. After a shutdown and wait for 30 seconds plus, I rebooted the phone and mail came down immediately. Until today it has been working fine, but after the latest update (18.xx.x) it is acting up again. I also note that on phones with a pre-18 iOS the mail works fine whether the forward slash is greyed out or not. My view is that if the above works, that’s fine, but the real problem is in mail after update 18. I concur with other users who lay the problem in Apple’s lap to fix.

Did you receive my earlier reply, Playpossum. Navigate to account settings/advanced/IMAP and type in a forward slash where the current one is. Then reboot. For what it is worth, this made the mail recover, and until this morning it seemed fine. This is not a real “fix” in my view because others have similar success with completely different “solutions”. The only common denominator is the iPhones have been updated to 18.xx. I have checked all of my acquaintances with iPhones, and no-one with an OS earlier than 18 is having a mail problem with Apple mail. The latest minor 18.xx update installed yesterday hasn’t helped and in fact has messed up my mail further, in that I am now unable to back out of the inbox to view the bin, drafts, sent mail, etc. Time to move elsewhere, methinks.

I called Apple Support today (December 5th) and after about 10 minutes doing a screen share and discussing which devices Mail works correctly and which do not, the Apple Support Senior Advisor confirmed that this is a known issue that Apple Engineers are working on. I asked if my support call would add another affected user vote to the existing case number and he confirmed, yes!

My strong advice is, if you are experiencing a Mail fetch and/or sync issue after updating to iOS 18 or 18.1.1, that you should call and report this...patiently waiting until they add you to the 'yes, this affects me too' case number.

This will help put more pressure on Apple to get this FIXED and stop trying to wait for some other feature release 18.2...

Having the same issue on an old ISP-based IMAP email account, getting a POSIX 61 error, intermittently receiving mail, sending not working. I shared details with a community manager for the ISP and they responded, "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."

So even though I have mail configured with incoming port 993 (SSL), and outgoing port 465 (SSL) as recommended by the ISP, iOS seems to also be trying to use port 143 on the side. Never had this issue until iOS 18 released. My Gmail, Outlook, and iCloud accounts all work fine. Issue still exists on the latest 18.2 Release Candidate (and all previous versions of iOS/iPadOS 18 and macOS 15)