Why is mail running so slow

One simple quick thing to try that might help is in Mail, do a Mailbox --> Rebuild.

It mght help and won't hurt.

It's running horrifically slow for me today as well. Something wrong on apples end?

I just upgraded to Mountain Lion. On Lion I had a nice and fast Apple Mail performance (MBP Retina). Now, the mailbox scrolling behavior in Mail Mountain Lion is much slower. Not very pleasant.

When I upgraded to L from SL, Mail was not slow but I couldn't perform searches anymore. I need to rebuild all accounts. What was curious, searching my mails didn't work properly even after rebuild. I need to rebuild a few times, and then everything was fine. I would follow the advise of sberman. You can rebuild with Mailbox -> Rebuild.

If I do the most simplest thing in Mail, like scrolling a list, I get the following:

(high CPU usage on a 2,66GHz i7)

What to do to get Mail running as fast and smooth as it did in Lion?

Could you have a look in the Console and post us, what is recorded there?

In Finder press SHIFT + CMD + U and you will be moved to /Applications/Uitlities. There you find the Console app. Fire up Console.

Left in the sidebar, being at "All Messages" should be something recorded what preocuppy your OS so much.

If there are some personal informations like your user, replace the user with "myuser" for example, before posting here.

hi and thanks. There is a LOT of stuff in that console, and I am just a normal user - no idea of that tech stuff.

So here is what can be read over and over again:

sandboxd: Mail(148) deny file-read-data /Library/Preferences/com.apple.mail.plist

That doesn't sound good. What can I do?

A possible solution here:

https://discussions.apple.com/thread/4139074

That worked. Thanks!

I'm not sure if the Library/Preferences/com.apple.mail.plist the only problem is, but the com.apple.mail.plist is obsolete since Mountain Lion.

If you want to go sure, not to harm you OS, follow the steps:

STEP 1

Quit AppleMail. We will backup the com.apple.mail.plist. Open a Terminal. Same procedure as before, in Finder press SHIFT + CMD + U and you will be moved to /Applications/Uitlities. You see the Terminal app. Double-click it and a window will appear, in which you can type manually commands. After it starts, copy and paste following commands. After each line press ENTER. The 2 command lines always start with the command cp.

mkdir $HOME/bkkup-mail-plist

cp Library/Preferences/com.apple.mail.plist$HOME/bkkup-mail-plist/user-com.apple.mail.plist

cp /Library/Preferences/com.apple.mail.plist$HOME/bkkup-mail-plist/system-com.apple.mail.plist

STEP 2

In the steps before we create a backup-directory in your $HOME, named bkkup-mail-plist and copied the plist-files in this directory. One file which is system-wide used and the other used for your own preferneces.

In the next step we will remove this files. You will be requested with your password to delete one of this files, so type your password, which you use to login. Again, after each line press ENTER:

sudo rm /Library/Preferences/com.apple.mail.plist

rm Library/Preferences/com.apple.mail.plist

That's all. Because of your message, that the system-task for Mail is driven by a daemon (sandboxd), it could be you need to restart. Post if this solved your problem.

Yes, Mail now being sandboxed I can certainly see the conflicts arising when Mail is trying to read an old com.apple.mail.plist file outside the containment.

The com.apple.mail.plist now resides in the Container folder

~/Library/Containers/com.apple.mail/Data/Library/Preferences/com.apple.mail.plis t

(if I can ever get away with that space between s and t)

1. Apple does sandbox mail.

2. Apple does not provide a proper transition for 1. when upgrading from Lion.

Anyway, with your help I managed.

Yes, the procdedure is not consistent. If Mail doesn't respect anymore ~Library/Preferences/com.apple.mail.plist, why it get disturbed by the presence of the file?

I suppose Apple intent to migrate the old prferences,

1. but forget to focus which file should be used in future and forget what was in past
2. and to delete files which are unnecessary.

It's quick 'n dirty.

To be fair, I have no such file anywhere else than in the container folder. And I upgraded from SL through Lion to ML without any clean install.

Also upgraded from SL to Lion, to ML, without performing one clean install. I had the file. Hmmm ...