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Mail not working on iPhone after iOS 18 Update

Hi guys,


After updating my iPhone from iOS 17.7 to 18, I encountered an error with my work email. It's showing "IMAP server is not responding."Our mail server uses TLS version 1.1. Does iOS 18 support this version? Can you confirm?




[Re-Titled by Moderator]

iPhone 12, iOS 18

Posted on Sep 16, 2024 10:04 PM

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Question marked as Top-ranking reply

Posted on Sep 26, 2024 7:41 PM

I added / (forward slash) in the IMAP Path Prefix field in IMAP account ( settings > Apps > Mail ) as suggested here in step 5 : 8 Steps to Fix Mail App Issues After Updating to iOS 18 and the issue is now resolved.

321 replies

Sep 17, 2024 8:49 PM in response to manojWijesinghe

I’d get the server to TLSv1.2 and with forward security configured minimally, and test again.


IMAP (read, receive) and ESMTP (send) are separate network services, so check both.


There are various ways to check the TLS and cipher offers by a server, and curl and testssl among those,:


https://stackoverflow.com/questions/40557031/command-prompt-to-check-tls-version-required-by-a-host


Also check the IMAP and ESMTP server logs for any failure-relevant details that might be included there.

Sep 20, 2024 8:49 AM in response to manojWijesinghe

Hi all, I Just check my Emails Securityfile Mail on iPhone 11 Mail/app IOS18 and it's no errors but it won't synchronize all my folders and emails. so yeah it is bug, don't panics hold your buts tight, they will fix it.

Oct 7, 2024 10:22 PM in response to mikefromfort wayne

mikefromfort wayne wrote:

 - Type a forward backslash “/“ next to the grayed out /
 - Now delete the grayed out forward backslash “/." Just tap to the left of the new backslash you typed and backspace to delete the grayed out backslash.

Are you sure you didn't already have a forward slash there? In my case, the gray forward slash isn't an editable character. You can't type next to it. When you insert a new slash, it just replaces the gray one.

Oct 9, 2024 1:39 PM in response to manojWijesinghe

Hello, somehow, self-signed certificates don't work anymore (even though they could be trusted before and most likely adhere to the requirements).


I was able to provide MDM payload with a Step-CA root certificate, its intermediate certificate and the signed certificate of the mailserver - it seems to be important that the chain of trust be completely working, including working DNS and alt name of the host. With iOS18.0.1, i have my mail back working.


If there are other bugs (like Prefixes on IMAP paths) i don't know, but i did not experience them and by looking in the SMTP/IMAP server logs, i was confirmed enough that TLS did not work.

Mail not working on iPhone after iOS 18 Update

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