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High Mail CPU with El Capitan

Since upgrading to El Capitan, I noticed the Mail application using a lot of CPU. About 80-90% sometimes.

Then going down to a few percent and then without any reason going up again.

Did a few times a "Rebuilt Mailboxes", but that did not help.


Any suggestions to repair this?

iMac, OS X El Capitan (10.11), 3.06 Ghz, 8 GB

Posted on Oct 10, 2015 10:33 PM

Reply
198 replies

Jan 6, 2016 1:17 PM in response to Grant Lenahan

While OS X is inherently much more secure than the-operating-system-that-shall-not-be-named, the only truly invulnerable computer is one that is BOTH air-gapped (not connected to anything else) AND completely shut down. Viruses that target the Mac platform are relatively rare at the moment, and they're generally not able to do as much damage for now, but both of those circumstances are beginning to change as Apple's market share continues to increase.


If you're very disciplined in your browsing and e-mail habits, your Mac can (probably) survive a bit longer without protection, but the time is rapidly approaching when a really good suite of security software is just as necessary on OS X as it is elsewhere. I personally believe that time has already come, so I'm continuing to run Avast for now. If that product proves to be a major player in the mail issue and I end up having to ditch it, I'll be running another product immediately.


And for whatever it's worth, I continue to maintain that, while Avast might be making the problem worse on some of the systems that are running it, I don't believe it's the actual root cause of the issue. My system and my wife's are both running fine with Avast up and fully operational (including Mail Shield), and there are several folks on this thread who are continuing to have problems with Mail, even though they've never installed Avast.

Jan 6, 2016 2:29 PM in response to brown607

Hello,


The problem you experience is very similar to the one I have described in your forum. You can have a look at my posts on this forum.


There is something wrong with Mail: Apple acknowledges it and is investigated (several people here, including me, have been contacted by Apple to perform a diagnostic on their system). So far no solution has been found and therefore, I encourage you to identify the mail account that causes the runaway and to use another mail program to consult it.


Regards,


P. Degiovanni.

Jan 6, 2016 3:23 PM in response to jeshuad

Hello,


Thanks a lot for this very interesting information. I'am one of the person who have experienced the Mail runaway (see my posts on this forum). The problem happens on one of my computers (a Mac Mini) with one of the IMAP accounts whereas it does not happen with a laptop, same OS version, same Mail version, same IMAP accounts.


However, my Mini runs Avast whereas the laptop does not run it !


So I'am starting some test: I have stopped Avast Mail agent for the moment and reactivated the IMAP account that makes Mail use all CPU. Usually, it takes two to three days before the problem starts again. So I will complete this Mail within a few days to give you the result of this test.


Regards,


P. Degiovanni.

High Mail CPU with El Capitan

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