Q: High Mail CPU with El Capitan

Hi Grant:

Do you also have such a large number of folders (a.k.a. mailboxes) in any of your IMAP accounts? Likely the other 99.9% of the cases do not accumulate so many folders either. E.g., if I enable only the Yahoo account (IMAP, only ~20 folders), everything is fine. Perhaps you know more than me, and it is true that the IMAP implementation in Mail is proper. If not, the jury is still out...

I still find it strange that other clients do not have the same problem, and I had no problems in Yosemite. Something has changed  in El Capitan. Of course, it could be just a configuration issue (I wish that was all, and I could change that and continue with my life!), but so far I tried everything suggested on this and other fora without any luck.

For the moment I am trying to clean up my old account, reducing the number of folders and hoping this fixes it.

> Curious - was the IMAP setting working in Yosemite?

For me,  yes.  Never had a problem with high CPU before I migrated to OSX.10 to OSX.11 and my 6 different email accounts haven't changed.   Although I did suffer from the "high CPU when composing a new mail in a different 'space' screen" problem (workaround,  don't compose in a different space).

The challenge is Mail's inconsistent.  At the moment,  it's behaving itself whereas a couple of hours ago it was consuming 250% and heating up the room.  I was using a VPN though,  so it's probably some networking malarkey and thread blocking.

No, not a huge number of mailboxes per account, generally < 10. But 9 accounts.

Note i didnt say simply config issues - most people have wound up with 3rd party software conflicts which occurred when those 3rd party apps conflicted with el cap.

Watch the trends.  100s of problems. The vast majority report - oh, i disabled X and it is fixed, or "oh, i changed from IMAP to exchange and it was fixed" or ....

I'm just watching and commenting.

G

Have you checked all your 3rd party software, especially from smaller vendors?

My mail archiving app stopped completely.  Upgrae. Fix.

Pascal and others,

After suffering for many weeks the same pains described i nthis thread (huge CPU usage, overheating, mails getting stuck when transferring them from one mailbox to another for filing purposes etc...), I tried most of the solutions recommended in the dozens of forums dedicated to this issue, be they Apple or non-Apple... to no avail.

I even tried switching to AirMail - not at all useful for my type of email usage, and also clogged with sluggishness, high CPU usage, etc.

And then I found this simple solution: remove Avast - worked wonders for me, 5 days without a problem

THANKS!!!!

HI G:

> Have you checked all your 3rd party software, especially from smaller vendors?

I disabled the Mail Act-on plugin and Avast, but did not help. But based on your (good!) lead, I'm now trying to start up in Safe mode (this should have all third party apps disabled) and see what happens. I'll post my experience when I'm done.

M

I also found the solution was to remove Avast. This stopped the main issues of very high CPU and hanging.

However there is still a niggling issue (which may not be related of course) - it frequently forgets the outgoing SMTP for the iCloud account and I keep re-entering it to be able to send messages.

Sorry my last post is missing the word "password", i.e. it forgets the outgoing SMTP password.

Safe mode did not help: Mail's CPU remained, as in normal mode, at ~200% for a few minutes. From this I would conclude that the problem is not due to a 3rd party app.

The problem, however, appears to be solved after I drastically reduced the number of mailboxes in that IMAP account from ~1500 to ~500; Mail's CPU is now back to normal (and the size of my email archive went down in the process).

Given that, except for the number of mailboxes, I did not change anything else plus the fact that Mail in Yosemite (as well as at least three other clients in El Capitan) dealt with ~1500 mailboxes without problem, the problem must be in Mail in El Capitan. I cannot prove it, but everything seems to point to that.

M

It's been 9 days since I disabled Avast mail shield and I have not had a CPU spike since.

Hi,

Thanks man!

After trying everything, I followed your advice, uninstalled Avast properly and the problem was gone instantly. Activity monitor was open when I clicked uninstall, Mail was eating +200, then fell to 2/5 after few seconds, and since then started to behave normally: it goes up to 20 when its window is active or when working on something, and goes back to 0/1 when inactive.

My mac is a 15" 2014 retina/2.5ghz/16G Ram/512ssd

So guys, go try Jeshuad solution, it might work for you also if you have Avast Installed.

I just want to add something: I am an Avast user from like a decade, on pc and on mac, never had a problem with a machine with Avast installed on it. It's probably some kind of incompatibility, not necessarily Avast fault, as there is user having the same problem without having Avast on their machines.

Good luck to all!

Ahmed Liuska

Hello,

After one week, it is time to give you news about my latest experiment since more and more people have experienced improvements by deactivating Avast:

Summary:

- I experienced Mail.app high CPU usage with one of my IMAP accounts. Surprisingly I experienced that one one computer (Mac Mini) and never on another one. Mail configuration and OSX version being identical on both computer, I noticed that one was protected using Avast and not the other one.

As indicated in my previous email, the issue was reproduced on the faulty computer under another user account, using Mail for the same IMAP server so this was not a user based problem.

- After five days of deactivating Avast mail shield and reactivating the problematic IMAP account, I had no experience of high-CPU hase by Mail.

- After some search on the Internet, I have read that there could be an issue with Avast Mail shied when the IPv6 is activated. I knew that there was no IPv6 activated at my home, not by my Internet provider and, finally not on the local network of the IMAP faulty account.  Ref: see for example https://forum.avast.com/index.php?topic=96665.15 ...

Consequently, I have tried the following fix: change Parameters in the Mail shield agent by deactivating both IPv6 and secured connexion analysis and then restart Mail agent. As of now, after one week of using Mail with the IMAP account that led to high-CPU, I experienced no problem!

I'am now experiencing the activation of the "Check secured connexions" while leaving the IPv6 option deactivated. I will tell you about the results in a few days.

Conclusion: at least for me, it seems that the issue is related to the settings of the Mail shield agent. If my next test succees, it may mean that you can still use Avast with Mail provided that you have the proper settings. This is certainly not satisfactory but at least, this gives a hint of the problem's location.

Last but not least, I don't claim that this solves everybody's problem. But everyone who experienced the high-CPU with Mail on a IMAP accound should first check wether or not Avast is installed and  then try deactivating at least the IPv6 option in the mail agent.

Regards,

Pascal.

Hello,

Strange... Many users have experienced that deactivating Avast mail shield solves the problem... An option is to do a clean restart of Mail with Avast mail agent off in the following way:

- first identify the IMAP account causing the problem;

- deactivate it;

- quit Mail;

- Move ~/Library/Mail to ~/Library/Mail-old;

- Be sure that Avast mail shield is deactivated;

- Reboot your computer for a clean restart (I'am not sure it's necessary but at least, it restarts all programs, including Avast);

- Then log in and restart Mail;

- Activate the IMAP account that causes the problem (in principle available accounts are still present in Mail's preferences).

If this doesn't work, it's quite puzzling... Of course, don't forget that Mail will rebuild files and database associated with your account since we have moved ~/Library/Mail but, after some time, its activity should go down.

Hope it helps,

Regards,

Pascal.

Thanks Pascal!

I have already removed Avast completely from my computer about a week ago, and then I did so many things I saw on this and other threads (like moving/removing many folders, including *.log and Envelope* files/folders and several others in ~/Library) that I do not remember whether I did this exactly. It might be worth trying... For the moment I'll take a rest (last week I spent most of the time on this, and now I need to do some real work!) since the CPU load is acceptable and at least I can work on my Mac. But, at least in my case, the cause of the problem is not resolved. Mail still uses ~200% CPU, but because I have less folders (and also a lot less emails), it only does it for about 10s each time it checks the server for new mail, once every ~15 minutes (I can live with that for the moment). Reducing the number of folders in my IMAP was like taking an aspirin when you have fever: the fever is gone, but the cause of the fever is still there...

Thanks again! Cheers,

Mariano

For those of us who don't use any of the (usually troublesome, rarely useful) anti-virus stuff...  When you are seeing lots of Mail CPU what do you see when you look at Mail, Window, Activity (or option-commmand -zero)?