Some Mail not sending in iOS 16

I’m having the same issue. Some emails go through without a problem, others just disappear like I never sent them. My customers are getting angry. It looks like I’m not getting back to them. Hopefully this gets fixed fast!!

Turn off Undo Send Delay in the mail app settings, or don’t close the mail app immediately after sending an email. It appears that if the app is closed during the undo send window, the email will disappear. This fixed the issue for me.

Email reply ends the email app. Goes straight to Home Screen. 16.1.1. Just updated. Turned off phone and restarted still have the same issue

It's not about being able to send emails or not, it's about emails that have been sent but once you leave the app and return to the app the email does not exist anymore, it is not in the sent folder, and the recipients have not received it. It is as if the email was never tight, sent or existed .

Every time I speak to Apple Support about this, it comes as a totally new issue for them as if they've never heard of it before, yet there are so many people complaining about the same thing.

Support for this issue does not exist and Apple/iOS is getting worse by the day

Same - and Apple act as if they've never heard of the problem, or rephrase the problem as if you're having problems sending emails rather than the fact that the emails have been sent yet disappear from the app, server and any evidence of having been written, sent or even existed.

It’s a feature on new software if you leave the app too quickly it undo sending the email.

Turn off Undo Send Delay in the mail app settings,

And if you don't leave the app too quickly, but send other emails which also do not appear in the sent folder…??

This is not confined to single emails, this is random, intermittent issue and where one one occasion I have been in an email dialogue, the recipient waiting on an email that I have sent, which they haven't received, and I'm sitting there waiting for their reply unaware that my email has disappeared into the binary either never to be seen again.

Also, I have reported this on three occasions to Apple and they have gone away to do their investigations and come back simply to ask me if I have updated my software, other than that they have not heard of the issue before and have no solution to offer for the problem

I am having the same issue with two different email providers. One just sits in the outbox until I resend it from the outbox and the other won’t send at all. It just keeps telling me the username or password is incorrect. I have deleted and the re-added the email addresses, restarted the phone several time, updated everything there is to be updated, but the issue persists

I'm afraid that is a different issue to the one where the email has been sent but completely disappears with no evidence of ever having been written or sent.

Your issue sounds like an outgoing server issue, or connection issue.

I wasn’t having this issue before ios16. Several users posting on this thread are saying the same thing. Maybe my emails aren’t “disappearing”, but there seems to be some issue with the new undo feature and several email issues on iOS 16

If you search "downgrade to iOS15"

and look up the tenorshare website, there are instructions on how to reinstall iOS15.7.

A user I support has a device that is enrolled with MobileIron specifically. It is occurring on their Exchange account that is setup on the native iOS mail client with 16.1.1. We have tried disabling the Undo Send Delay feature last Friday 11/18; that seemed to have resolve the issue but just received a message from the user yesterday 11/20/2022 that he is getting the "Cannot Send Mail - An error occurred while delivering this message," prompt again. This user only has an Exchange account setup within the native iOS mail client.

I disabled the “undo send” feature already and that has rectified the issue with my Comcast account, but not the other email account I am also having the issues with.

turning off send delay worked for me, or not closing app before delay period.