Mail not working on iPhone after iOS 18 Update

Yep. There is something wrong with the Mail app. Here's my backstory:

Before posting my suggested solution, I spent around two hours Wednesday (Sept 18) on a tech support call with senior Apple advisor regarding this issue. Eventually they had me install MS Outlook. We successfully connected to my mail server using Outlook.

The Apple senior advisor said that if I could get the screen shots and application logs uploaded to them, he might be able to get back to me by Tuesday (Sept 24), because he was out of the office on Monday (Sept 23). The advisor was personable and pleasant. I have nothing against him personally. Nevertheless, he was not empowered adequately to resolve my issue or escalate it in a timely manner. So, I'm throwing Apple as a company under the bus for creating a problem with the Mail app they could not resolve for me or others.

I could not wait to resolve the issue. I am no fan of MS Outlook. So, I looked to other third-party mail apps.

Moving off of Apple Mail to a third-party mail app is a viable solution when:

• Your business email accounts are dead in the water because of the issue
• Apple support is unacceptably slow to respond to the issue
• Apple's time to market with an updated release that fixes the issue is unknown
• Perceptions of many long-time users are that the overall stability is in question
• Other available solutions work

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.

Knowing what I was likely to be letting myself in for, I decided not to update my phone but update ipad for a test.

I run my own mail server with a self signed SSL certificate.

Updated to iPadOS18.3

Deleted Mail account.

Set up Mail account with working settings from iPhone on iOS 17.7.2

I was asked to review details and trust for my certificates which I did.

Opened Mail app, all emails visible and readable.

Replied successfully.

As soon as Mail app checked for new mail I got:

The mail server X is not responding. Verify that you have entered the correct account info in Mail settings

Unable to create a secure connection to the server (“bad certificate format@ -9,808)

Set up outlook connection to

my account without issue!

Lots of frustration as OSX Mail was working fine as was another iOS email client (AirMail).

I went onto the Internet and used WebMail to tell me what Server settings were acceptable to iOS.

My other Mail clients were using imap.XXXX.com.au and working fine but for some reason iOS mail wanted mail.XXXX.com.au according to WebMail. I changed the Server name and iOS Mail now works fine on iOS 18.1.1.

This tells me this may be a function of your email service provider's server settings and how they have (or havent) updated them for iOS 18. Also there may be other settings listed in the WebMail configuration requirements for iOS that iOS Mail needs. My suggestion is check each one against the WebMail advice.

Eirrol64 wrote:

I too experienced issues but only on my iPhone. I contacted support, deleted the account that wasn’t working. Reloaded it and it worked

Deleting and re-adding an email account that's not working properly is always a good first step. It doesn't take long and it fixes the vast majority of issues. It does so because it loads fresh settings for the account.

Glad you got it working!

Updated to 18.1.1 and same issue. I ended switching to an email app like Edison, Spark and my email is now working.

I think there are/were multiple issues, which confuses diagnosis. As a workaround I had disabled imap-IDLE on my (Dovecot) mail server and my iOS 18.2 iPhone was able to get mail, but was still hanging at times.

After updating to iOS 18.2.1, I re-enabled imap-IDLE and mail seems to be working normally. It uses imap-IDLE (near-realtime delivery) when the mail app is open and fetches every 15 minutes otherwise. It gets the mail messages and alerts correctly.

I contacted Support via chat and was told to delete the email account and re-add it. It worked.

MrHoffman wrote:

I’d think that a mail server not minimally offering TLSv1.2 and forward security would be a more interesting question to investigate and potentially address, …

And for completeness, this may be a bug in the iPhone mail client, too.

——-

Appears that at least for my server, checktls and several other online tls and Mx testers all say TLS works and 1.2 is available and functioning…. One service griped about the sectigo certificate and was looking for the intermediate, but it finished the TLS tunnel and reported all was well. Meanwhile, the mail app on my macOS machines are happily chugging new mail off this server…. So we can stop blaming the mail server.

The only place where this IMAP issue is happening for me is in iOS and iPadOS 18.0 mail app clients. And looking at the server log, it looks like the mail app just decides to go silent and doesn’t even begin negotiating the mail list at all. (I’m not posting the log file…. Too much to redact there)

[Edited by Moderator]

After struggling for the last couple of months with not being reliably able to check my IMAP email on my iPad running iOS 18.x, in frustration I reached out to my ISP, which happens to be CenturyLink. Their automated help system informed me that:

We are currently experiencing a technical issue. The Apple iOS 18.1 update is causing widespread IMAP failures with email providers and at this time they have not published a resolution. We apologize for this inconvenience and we thank you for your patience, but please note that this new update was implemented by Apple. Our server settings do not change as a result of any company's firmware updates and therefore Apple needs to determine and publish this resolution. Our technical team is however testing and working to find how we can best assist in these matters going forward. Please contact Apple support. To access any mail in the meantime, please access your email through our Webmail Platform. Thank you for your patience and understanding.

Apple developers, please fix this. From reading through this chain, it's been a recurring issue over various iOS releases. Come on - you're better than this!

After three hours of troubleshooting I found another workaround. My imap 3rd party email stopped importing today, about three days after I had updated to iOS 18.2 on my iPhone SE2020. NO incoming and outgoing swooshed as tho it was sent, but never arrived at destination. Gmail incoming to Mail app was flaky too, but okay in Gmail app so it was t just the one server. My iPad is too old for iOS 18 and Mail works fine there, as it does on the Mac. it’s a phone/ios 18.2 Mail issue.

I did everything suggested- replaced Mail app, deleted Mail accounts and added them back. Checked settings. Rebooted. It wasn’t working. Provider was stumped and at least got me connected with the web version of their mail so I could at least access messages, albeit inconveniently.

Then I remembered I had enabled Aura “shield” — not the full VPN. As soon as I turned that off, Mail started flowing. Previously it had no effect on Mail but now it had bottleneck everything. I’ve contacted them and also put in a bug report to Apple— something isn’t right with ios 18.2 and mail, still. But if you have a vpn or security “shield” — try disabling it. It’s less safe, but at least Mail is arriving now. The Mail app is gradually rebuilding my inbox, but now it doesn’t seem to know who the sender is for hundreds of iCloud emails. The imap 3rd party mail, on the other hand, is showing up correctly. Crazy business!

Solution!!! Disable VPN. Restart iPhone. And email works. Just to let you know this is no except able. Checkpoint :Zone alarm uses VPN for there secure service and so does Verizon. Apple needs to get there act together. The email was working fine with all vpns… but until iOS 18**. It has been the mother of all &&&&. Please fix this Apple thank you

It looks like the OP is using Zimbra (which uses the Postfix as its MTA). For those who use Postfix, but especially for those using Zimbra, you may want to have your admin look at ZBUG-4531 and this post https://forums.zimbra.org/viewtopic.php?t=72998. Basically, whatever Apple changed in Mail from iOS 17 to iOS 18, it's causing Zimbra/Postfix to generate egregiously long list of conditions for IMAP queries on the back-end, causing accounts to lockup for minutes if not hours while the query is running. While Zimbra/Postfix should definitely be limiting max conditions, Apple absolutely needs to do a better job of debugging and testing. Really unacceptable for a trillion dollar company with the kind of resources they have to failed like this and then proceed to not fix it.

Like many I first had this issue w/ iOS 18. But I don't think I noticed it until I got my 16 Pro Max. Regardless, I can't believe people still have this issue and I can't believe Apple has not addressed it. Here is what I did and I suggest you try:

 - Get your phone …

 - Go to Settings … scroll all the way down to Apps …

 - Go specifically to: Settings>Apps>Mail>Mail Accounts>Select your mail account>Account Settings>Advanced

 - In the group “INCOMING SETTINGS,” the second line should read: "IMAP Path Prefix /“

 - You may notice the forward slash “/“ is grayed out and not the same contrast as the three words prior.

 - 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.

 - Press "Back" and then "Done" and back out of Settings.

 - Finally, perform a hard reboot of your phone in the following order: 1. Press and release the left outside volume up button. 2. Press and release the left outside volume down button. 3. Press and HOLD the right outside power button UNTIL the phone shuts down, restarts AND you see the Apple. DO NOT slide the power down “slide button” during the shutdown. Keep your finger on the power button UNTIL you see the Apple upon restart.

The above procedure solved my email issues.

I discovered a solution to this: Spark Mail

After upgrading to iOS 18 and iPadOS 18 on my respective devices, and wasting hours trying to make changes to my Mail app configurations and debugging via my mail server as per the guidance from various contributors to this thread, I began a search in earnest for a replacement to Apple Mail.

Spark Mail is $59/year (USD) for an individual user like me and after trying it out, I’m kind of grateful that I encountered this issue with the Apple Mail app, because without this issue I never would have discovered Spark, an email app for my iOS, iPadOS and MacOS devices that provides a significant productivity boost (even though I’m already subscribing to SaneBox) and it solves the blocking issue described in this discussion thread.

hth some of you who are held hostage by this situation. I’m not affiliated with the makers of Spark in any way. I just wanted to share the solution I landed on.