High Mail CPU with El Capitan

Shame on Kerio.

Hi Grant,

I found, that my troubles with high CPU peak with Mail.app were probably caused by spotlight conflict. As I cannot explain why this happened, above steps helped me. Before I tested this, I exchanged battery, reinstalled Mac OS X from the scratch and definitely let Spotlight index all my files not overnight, but over multiple nights. I agree with you, it's weird, but now I don't see so high Mail.app CPU usage as before. I didn't want this thread to lose its focus. ;-)

Enjoy,

Pavel

Thanks. Unfortunately this did not improve things here.

I, however, identified the reason for the message in the Activity Window that indicated that Mail was continuously downloading a few hundred emails each time it checked for new emails. In my case the problem was a corrupted message in one of the folders. It took a while to find it (looking at the log files in some detail); from the moment I deleted it I no longer get the repeated download. Unfortunately this was in the account that does not trigger the high CPU usage, so it did not solve my problem. It may be that there is also a corrupted email somewhere the other account, but I do not see any hint of that in the log files, and I cannot easily track it down since I have a few thousand emails there.

Just wanted to share this.

Actually i really tried all of the suggested solutions, but a few days on with even Exchange account activated, Mail behaviour is back and did not change at all. The high CPU usage consumes much to much energy and i nearly can't use my MacBook Pro anymore while Mail is open! I can count down the battery charge. That's really crazy. And for this it's only Mail!

The fans spin up each time the program is just synchronising the latest emails... El Capitan is crap and so is Mail...

I don't know what to do, now?...

Best.

I found a new solution which actually helped me! Mail now works absolutely fine:

Go to your account > choose the tab to the right with advanced options and turn off "Automatically take account settings"

What you need to know, is the way mails are requested with IMAP from your provider as you have to manually set the port and the authentication mode, like in my case port 143 and mode "password".

Do the same thing you do for the SMTP settings in the Tab to the left, general account settings. Again disable "Automatically take account settings" (or like it is called in English).

BUT: You usually have to set a DIFFERENT PORT there!

After having set all of these account settings manually, all problems with the high CPU usage and crazy fans were gone!

... so far...

This did not change anything in my case, unfortunately... But thanks! And any other suggestion is welcome.

I have been experiencing the same problem since I upgraded to El Gran Capitan. I have an old macbook pro early 2011 and since I replaced my old HD for an SSD and did a fresh installation my system was faster than the day I bought it...until I started experiencing this issue with Mail! I have been trying to find a solution and tried to erase the log files as somebody mentioned but nothing happened; my CPU usage was always over 75% (my RAM usage was fine though). I tried to narrow down the problem and deactivated all my mail accounts (9 in total) and then the Mail CPU usage went back to normal. Then I started to activate them back one by one and found out that most likely one of the mail accounts was creating the issue. Now I am accessing that particular account trough my iPad while keeping it deactivated in my laptop and it seems to be working fine, my CPU usage is back to normal.

I hope this helps

I knew that it is an issue with Mail and some accounts and this was already stated from others, too. So sometimes it's the kind of login, sometimes it's the size of the account and so on...

BUT: It's absolutely no solution to deactivate Mail-accounts to not cause high CPU usage from the Mail-app.

If that's really what you like, i would suggest to turn of your Mac book so the CPU usage should go rapidly down...

You don't seem to be able to read a text properly. What is relevant of the post is the method to find out which of the mail accounts is creating the issue with Mail, then once you know it you can find your own solution. In my case I have kept it deactivated because it is a mail address I don't use much and I can handle it from my phone. In case it would have been one of my main address I would have thought about a different solution.

Then i read everything right! It's absolutely no solution to turn of an account and it's absolutely logic to test which account causes an effect... so nothing new.

I had the same issue and looking over the logs, it seemed that there were corrupt emails which resulted in an endless loop of checking/downloading mail. We were under the process of migrating our accounts to a different server.

Our email accounts were using a SmarterMail server. I'm not sure if that was the culprit as I checked with the datacenter and was told that no other users were experiencing this. We migrated our mail to Rackspace and everything has been working fine ever since.

There may be, however, something that could be tried (I didn't get a chance to fully try it as we had to migrate). Rackspace uses a tool called Bit Titan migration tool to migrate email, which we used to migrate my IMAP email to their Exchange account (notice that the new account is in fact Exchange and this may have helped solved the issue).

However, what I was planning on doing, is using their tool (which is in fact created by Bit Titan - https://www.bittitan.com/products/migrationwiz/) to create a secondary IMAP account on my server and move from one account to another. This, because Bit Titan actually detects corrupt emails and doesn't move them so there's a safe chance that those emails which may be causing the issue wouldn't be migrated over. After that's done - and if you have access to the mail server - you can rename the accounts so that all the correct email is actually under the right account. If you don't, I suppose you could migrate it back.

Think of it as using a strainer to leave out all corrupt emails.

I haven't fully tested this solution using the same email server back and forth, but considering all the issues with El Capitan, it may be worth a shot.

Hope it helps!

if its index corruption, which can occur, consider re-building the mailbox indices.

Grant

Tried this several times... the issue seems more email corruption on the mail server itself, which doesn't matter how many times you rebuild, you must remove those corrupt emails at the server level before they sync with the mail program.

BTW - I've seen something similar to this happen on Outlook as well (same mailbox)

I have this problem, and the issue appears to be due to corrupted mail server mailboxes that OS X Mail can't handle - It keeps downloading mail, in an infinite loop.

This happens on a specific IMAP mailbox with thousand+ folders (not sure how many, but a lot..) and doesn't happen to other IMAP mailboxes that have several hundred folders.

BTW The Mail server that I am having problems with is actually running OS X El Capitan Server!

No such folder: /Library/Containers/com.apple.mail/Data/Library/