My mailboxes do not load.

Quit Mail. Force quit if necessary.

Back up all data. That means you know you can restore the Mail database, no matter what happens.

Triple-click the line below on this page to select it:

~/Library/Mail/V2/MailData/Envelope Index

Copy the selected text to the Clipboard (command-C). In the Finder, select

Go ▹ Go to Folder

from the menu bar. Paste into the box that opens (command-V), then press return.

A Finder window will open with a file selected. Move the selected file to the Desktop, leaving the window open. Other files in the folder may have names that begin with "Envelope Index". Move those files, if any, to the Trash.

Log out and log back in. Relaunch Mail. It should prompt you to re-import your messages. You may get a warning that the index is damaged and that Mail has to quit. Click OK.

Test. If Mail now works as expected, you can delete the file you moved to the Desktop. Otherwise, post your results.

Problems such as yours are sometimes caused by files that should belong to you but are locked or have wrong permissions. This procedure will check for such files. It makes no changes and therefore will not, in itself, solve your problem.

First, empty the Trash.

Triple-click the line below on this page to select it, then copy the selected text to the Clipboard (command-C):

find ~ $TMPDIR.. \( -flags +sappnd,schg,uappnd,uchg -o ! -user $UID -o ! -perm -600 -o -acl \) 2> /dev/null | wc -l

Launch the Terminal application in any of the following ways:

☞ Enter the first few letters of its name into a Spotlight search. Select it in the results (it should be at the top.)

☞ In the Finder, select Go ▹ Utilities from the menu bar, or press the key combination shift-command-U. The application is in the folder that opens.

☞ Open LaunchPad. Click Utilities, then Terminal in the icon grid.

Paste into the Terminal window (command-V). The command may take a noticeable amount of time to run. Wait for a new line ending in a dollar sign (“$”) to appear.

The output of this command, on a line directly below what you entered, will be a number such as "41." Please post it in a reply.