I can't pin this bug to anything specific so I'll try to give as much info as possible. This bug started about 3 or 4 months ago for me. But around that time I did enable the "Today" inbox and that is what I use 90% of the time now. The problem is I'll swipe left to send a handful of e-mails to the trash then leave the app. Next time I check e-mail most of them are back. I have to swipe left to delete them all over again. Usually after two or three deletes they stay gone. What gives?

I'm running iOS 9.3.4 & OS X El Capitan 10.11.6.

UPDATE: I downloaded Airmail. In Airmail I added my @icloud account and one of my @gmail accounts. @icloud.com e-mails still won't stay deleted, they keep reappearing (not all, just random ones). @gmail seems to be fine. So it doesn't appear to be the app that I'm using. Is this an issue with @icloud email?

UPDATE: I tried rebuilding the mailbox twice using the default Mac Mail app. No joy. After it was rebuilt I selected about 10 emails to delete, press delete, it says in the bottom left "Moving Messages", stays that way for 2-10 minutes, then finally goes away. I switch to my gmail inbox then switch right back to the icloud inbox and they are back again. I've repeated this many times. When it says "Moving Messages" in the bottom left it seems to take a very long time. Very frustrating. Sometimes I've seen an error message popup saying it couldn't delete because mailbox was busy (something like that).

I also tried accessing mail via www.icloud.com, after selecting a handful then deleting, and waiting a long while, it would throw a message saying it couldn't delete them. I then tried deleting 1 at a time via the icloud website and they delete but it thinks for a long time before it actually disappears. So it seems like deleting is veeeeery slow and works 1 at a time via icloud website, but multiples don't delete/timeout or something.

Any help would be appreciated! I couldn't find any solutions on the Apple forums.

UPDATE: I changed my icloud password just in case it was something malicious. Didn't help. I did find these: https://discussions.apple.com/thread/6560166?start=0&tstart=0



Do you think icloud is having issues and it's still running slow and that is what is causing my delete issues?

  • This is now happening to me with macOS Mojave, iOS 12, just my iCloud messages will not delete. I've tried everything including using iCloud.com. Random emails will just not delete and will randomly pop back into my inbox. Super frustrating.
    – teewuane
    Jun 17, 2019 at 17:43
  • @teewuane Yeah it’s frustrating. It hasn’t happened to me in a very long time but I did notice about a week ago it happened again. I tried deleting a handful of email from iCloud acct via quickly swiping on iPhone. Then I went to trash and said delete all. A minute later they were back in my inbox. Ugh.
    – gfrobenius
    Jun 17, 2019 at 19:02
  • Yeah, it seems when I delete them very very slowly then it will work okay, but if I try to delete a handful semi quickly it will throw the error. I'm sitting on a call with apple right now. Hopefully they can figure it out :/
    – teewuane
    Jun 18, 2019 at 16:11

2 Answers 2


This also occurs in Outlook for iOS.

It's an iOS threading (GCD) issue of one of two kinds, either:

  1. GCD places low-priority on threads to which calls for "delete" are dispatched, and defers to any and all other operations on, like, any other thread; or,

  2. GCD stops waiting for a condition to be met on the mail server side, suspends or kills the thread in favor of others, and then fails to resume or reinstate the thread at a later time.

It could also be improper implementation of GCD in a networking component of iOS, which happens easily enough for programmers with less than 20 years of experience with multi-threading behind them.

  • Thanks, but I use Outlook for iOS for my work e-mails (not an @icloud.com address) and have not had an issue with it at all. And I swipe fast to delete many all the time. Based on new info I added to original question I think it is pointing more towards an @icloud.com issue since my @gmail.com and other work accounts seem to work fine.
    – gfrobenius
    Aug 11, 2016 at 20:03
  • No, it's a known issue, according to the Microsoft tech support rep I contacted on this very issue. That doesn't mean you're having the issue, but it ranks high in the list of complaints from users of Outlook for iOS.
    – James Bush
    Aug 11, 2016 at 20:06

My issues was not an issue with the iOS Outlook app (which I do use as well). This was not an issue with any of my work emails or gmail address or yahoo address, etc... It was only a problem with my @icloud.com address. I finally gave up and just started deleting years worth of e-mails via www.icloud.com. It took a long time because like I said, deleting was VERY slow. It did seem to gradually get faster the more and more e-mails I deleted. After deleting about 3 years of e-mails (and along the way deleting them from trash also), the problem has now seemed to resolve itself. Deleting/moving/etc from www.icloud.com still seems slower that I think it should be, but at least I can delete icloud e-mails using the mail apps on my iPhone and they no longer reappear.

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