10.11.2 El Capitan: Mail keeps quit and asks for rebuild

I am having the same problem everyone else is having about mail. Keeps quitting multiple times a day; so frustrating; content is blank and no message shows up; I am constantly going to my iphone to read email now. Also having the same problem with deleted messages showing back up. And ones I delete on iphone not deleting anymore on my mac. I will try your solution to see if it helps , but since I am not a techie, I usually like apple to fix. However my mac is beyond applecare now and I can't get support.Glad there is this forum so I can learn others have the same problem.

Please fix Apple

Problem solved!

And I've come to the conclusion that this is not an 10.11.2 El Capitan issue.

The essential problem was that Mail is out of sync with iCloud. When opening Mail it starts to download (sync), gets hung up at some number and then just stalls. In addition it keeps re-downloading emails that were perviously deleted. Quite Mail and relaunch did not solve this. Delete various Library files did not solve this. Here is what I did that finally worked.

Option 1

Open System Preferences, iCloud, and then Sign Out … but be careful. You will warned that doing so will delete files from you Mac for Contacts, Calendars, Reminders, Notes, etc. I only have these in iCloud so there was no problem deleting. However if you, for example, have any Notes 'On My Mac' they will be deleted. The solution in that case is to move everything over to iCloud. Once you're confident you can safely 'Sign Out'.

After signing out, sign in again. There will be a checkbox if you want to use iCloud for Mail, Contacts, Calendars, Notes etc. Leave it checked and complete the sign in – this means iCloud data will be sync'd to your Mac. Then the next time you first open Mail, Contacts, Calendars, Notes, etc the first thing that happens is syncing with iCloud. I did this with my wife's iMac (experiencing the same stalled download problem) and bingo … 'downloading' started, and completed! Previously deleted email did not return. All is now normal, and with super quick syncing among her devices.

Option 2

My MacBook was more challenging. In my case I had migrated most email folders (and about 2,500 emails) to iCloud in an attempt to solve the sync problem. After confirming they were in iCloud, I deleted them from 'On My Mac'. My theory was to put all my email+folders in iCloud only and it would stay in sync. This did not work – I was still stalling on 'downloading' and previously deleted email was reappearing.

So, I opened System Preferences, iCloud, and then Signed Out (making sure everything was safely in iCloud). I then Signed In with the box checked for Mail, Contacts, Calendars, Notes etc. Then opened Mail and it began to download … but this time completed! It took some time because it had to download 2,500 emails. It also does this in two stages, first it counts of the number of emails to be downloaded, after which it does the actual download (count + progress bar). When complete I was perfectly sync'd, which I confirmed by sending several test emails to myself and my wife. They all worked perfectly. I deleted, trashed … they were gone and did not reappear.

Once fixed, I moved my iCloud folders back to 'On My Mac', which I prefer for better security – email I want to keep is only on my Mac and not in iCloud. You can decide if this is important to you. When complete I deleted the folders from iCloud with no problem. I then did several more test emails and everything has returned to normal with super quick syncing among my devices.

Hope this helps.

I'm having this issue since the first release of El Capitan. But in my case the issue is not related to the iCloud account but to two other accounts (IMAP) by a local provider. I have tried to quit everything (trashing, preferences rebuilding the index manually, downloading again all the mail) without success. Now I'm with the version10.11.3 and still the same. I also have to trash the logs files every week as they grow up to 60 Gb and more ! It seems that mail doesn't communicate well with the accounts (not only iCloud), re-download mail as told above (trash & draft) but sometimes more, than that. I've also noticed when I wrote a medium or long message it quite oft as it can't synchronize the automatically saved draft. For me it's quite clear that the issue is in Mail and not by the account. The same account under Yosemite works perfectly ! At that time I haven't found any solution to solve my problem ant it comes very annoying, hope Apple will fix that issue with the next release as mail is quite unusable for the moment.

Not sure if this will help anyone, but my solution seems to be the fact that Avast was conflicting with Mail. I simply went into the Preference panel of Avast, and turned off the Mail Shield and everything is fine. Hope this helps.

Great tip, thanks. Even after a complete re-sync with iCloud (option 2 in my previous email), Mail would still occasionally stall on 'downloading …'

I'm also using Avast, so I disabled Mail Shield as you suggested and everything downloaded with no problem. I was, however, bothered by the idea that Mail was not protected, so I clicked on 'Settings' below the 'Disable/Enable' button. That opened a window where you can enter 'Excluded servers' … I added Apple's Mail server. We'll see if this works okay. If not I'll leave Mail Shield disabled.

I'm more and more convinced this is not an Apple or El Capitan problem but instead related to other software that interferes with the syncing process. When everything is sync'd and working properly iCloud is a thing of beauty in it's user friendly simplicity.

I just tried this. I excluded my mail servers in Avast. I closed Mail. Restarted Mac; opened mail; deleted all 90 drafts. ( this time they didn't just reappear like before); then deleted my Trash.

I have opened and closed Mail several times and all seems fine. No more hundreds of drafts. No more missing content.

I must say that I got my content back first before excluding stuff in Avast when I deleted the extension for seeing who had read my emails( forget now what is was called; Signal maybe?) this helped the content issue but not the many drafts issue.Someone in forum mentioned several extensions that were interfering with Mail. I noticed I was using one and as soon as I deleted the extension my mail loaded up fine.

But again I still had a lot of drafts which seems fixed with Avast issue.

So maybe two things were interfering with my Mail? The bad extension and Avast?

I have been suffering from this problem for several weeks, if not months. I believed it started after upgrading to El Capitan. I tried the usual suggested solutions (e.g. rebuilding the Mailboxes, removing the Envelope* files, etc). However, sooner or later, the crashes would eventually come back.

I now believe that the problem was caused by some corrupted mail/folder of mine on my IMAP account. Unfortunately Mac Mail could not handle this (other email clients have been more robust).

The way that I managed to solve the problem was with some re-organisation of my old email. In particular, I used Thunderbird (since Mac Mail kept crashing on me) to "Archive" all messages of mine (ie. effectively retiring old mail folders in favour of newer folders named Archive/2015, Archive/2014, etc). In the process, I discovered some very large old messages (20 MB each or so) that I got rid of/deleted. I eventually migrated all messages (in the hundreds of thousands) into new "fresh" archive folders (created by Thunderbird) and deleted the old mail folders.

This "cleansing" process apparently took care of whatever the corruption was. I can now use Mac Mail again.

I am posting my solution here in case it is useful for somebody else.

My Apple email has been quitting for the past 3 months. I have called Suport and taken the macbook in for report. They have done everything and have not been able to correct he problem.

Apple has not done anything about this.

They are incompetent and lazy.

Mars