Mail.app takes up 150-350% CPU because of one single account

[MacT101]

Hi everyone, I'm desperate:

I have 3 IMAP accounts, all the same domain, same host (the German t-online.de). All of them have the same settings in mail.app

The problem:
- my mac is running ridiculously slow and heats up: activity monitor shows that mail.app takes up between 150 and 350% CPU (I don't know how that's possible, but whatever).
- I noticed, one of the 3 accounts (let's call it account A) doesn't automatically receive emails. Not even when I hit "Get new messages". It only receives new messages when I quit mail.app an restart it. The other 2 accounts work normally.
- When I go to mail->preferences ant disable account A, my problems seem to go away completely and mail.app is back to using about 15% CPU in Activity Monitor
- additionally: for account A the Mailbox -> Rebuild function is greyed out. For the other two accounts it isn't

I already deleted the envelope files in library->Mail->V3
I already deleted account A and set it up again.
I already completely deleted a plugin called MailTags which I first thought was causing the trouble right after updating to El Capitan. It seemed to have worked for a day but then the trouble seemed to be even worse than before.

I really hope you guys can help me out here!! Thanks!!

 

[Goatllama]

Hmm, so what is different about that account? Does it have a huge amount of email in it? Anything you can think of? When did this start happening?

 

[MacT101]

Hmm, so what is different about that account? Does it have a huge amount of email in it? Anything you can think of? When did this start happening?

Not much less than the other one. Like 4GB... Could that cause such behaviour? I'm currently running a system scan with Avast Mac Security. Maybe that makes me a bit smarter?

 

[Goatllama]

It could. It could also perhaps be the contents of one particular email - are there any emails in that account that have attachments, etc.?

I don't know if Avast will really find anything, but if it does that would be pretty cool. My last experience with Avast was that it hates iTunes and doesn't want it to work.......

 

[MacT101]

It could. It could also perhaps be the contents of one particular email - are there any emails in that account that have attachments, etc.?

I don't know if Avast will really find anything, but if it does that would be pretty cool. My last experience with Avast was that it hates iTunes and doesn't want it to work.......

The majority of the mails have attachments. Should it then help if I create a mailbox "On my Mac" and move all the mails from "inbox" and "sent" there or how can I find an get rid of the mail that causes the trouble?

 

[Goatllama]

Well, process of elimination would work best there. Make a backup of any/all emails you don't want to lose, then delete half of your emails in this particular trouble-causing mailbox. If issue persists, delete half of those, etc. Narrow it down 'til we know which emails could possibly be causing the problem.

 

[flowrider]

I had the same issue with something (I don't recall the name) that had HP in the name. I tried to locate it and couldn't find it. I kept removing it from Activity Monitor and 2 seconds later it would pop back in. It was on my boot drive of course. I finally restarted on my backup drive and erased and reformatted my El Cap boot drive. I then started from a third (Yosemite backup drive) and cloned the El Cap backup drive to my SM951. That of course cured the problem. Was probably some kind of Trojan Horse I picked up, god knows where

Lou

 

[MacT101]

Still couldn't resolve the issue... Apparently I can't even delete emails any more. Every email I delete is back after like half an hour. Seems like they are just gone on my machine but get pulled from the server again. Any advise?

 

[RedRaven571]

Not much less than the other one. Like 4GB... Could that cause such behaviour? I'm currently running a system scan with Avast Mac Security. Maybe that makes me a bit smarter?

On my system, it appears that Avast WAS the problem. Mail was consuming 150-200% CPU and running CPU temp up to 70 C while nothing else was running; this morning, on a whim, I turned off the mail 'shield' in Avast and, so far, mail seems to be behaving normally. At this point, at least on my machine, it seems that Avast was causing the problem. YMMV.