Q: Mail Quits Repeatedly in Yosemite

Try restarting your Mac in Safe mode:

- Shut down your Mac

- Wait until your computer turns off and after that press the Power button

- Right after you hear the startup tone, press and hold the Shift key

- Release the Shift key when you see a grey Apple sign and the progress bar below this sign

- Once you see Desktop, start a Disc Utility scan to detect and repair file system errors (don't forget to choose your main hard drive)

- Click on Verify Disc and then, if asked to fix problems, on Repair Disk

- After this, click on Verify Disc Permissions and then on Repair Disc Permissions

- After the process is finished, shut down your Mac and turn it back on after about 30 seconds

Launch Mail application

Do a backup.

Quit Mail.

Go to Finder and select your user/home folder. With that Finder window as the front window, either select Finder/View/Show View options or go command - J.  When the View options opens, check ’Show Library Folder’. That should make your user library folder visible in your user/home folder. Go to Library/Containers/com.apple.mail.  Move the folder com.apple.mail to your desktop. You must move the entire folder, not just the contents.

Restart, re-launch Mail and test. If the problem is solved, recreate any required Mail settings and import any emails you want to save from the folder on the desktop. You can then put the folder in the Trash. If the problem remains, return the folder to where you got it replacing the one that is there. 

Information learned from Linc Davis. Thanks to leonie for some information contained in this.

Crashes/quits unexpectedly

Syncing Notes using iCloud? Try System Preferences/iCloud, deselect Notes syncing, wait a couple of minutes, and then reselect it.

Launch the Console 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 and start typing the name.

Step 1

For this step, the title of the Console window should be All Messages. If it isn't, select

          SYSTEM LOG QUERIES ▹ All Messages

from the log list on the left. If you don't see that list, select

          View ▹ Show Log List

from the menu bar at the top of the screen.

In the top right corner of the Console window, there's a search box labeled Filter. Enter the name of the crashed application or process. For example, if Safari crashed, you would enter "Safari" (without the quotes.)

Each message in the log begins with the date and time when it was entered. Select the messages from the time of the last crash, if any. Copy them to the Clipboard by pressing the key combination command-C. Paste into a reply to this message by pressing command-V.

The log contains a vast amount of information, almost all of which is irrelevant to solving any particular problem. When posting a log extract, be selective. A few dozen lines are almost always more than enough.

Please don't indiscriminately dump thousands of lines from the log into this discussion.

Please don't post screenshots of log messages—post the text.

Some private information, such as your name, may appear in the log. Anonymize before posting.

Step 2

In the Console window, select

          DIAGNOSTIC AND USAGE INFORMATION ▹ User Diagnostic Reports

(not Diagnostic and Usage Messages) from the log list on the left. There is a disclosure triangle to the left of the list item. If the triangle is pointing to the right, click it so that it points down. You'll see a list of crash reports. The name of each report starts with the name of the process, and ends with ".crash". Select the most recent report related to the process in question. The contents of the report will appear on the right. Use copy and paste to post the entire contents—the text, not a screenshot.

I know the report is long, maybe several hundred lines. Please post all of it anyway.

If you don't see any reports listed, but you know there was a crash, you may have chosen Diagnostic and Usage Messages from the log list. Choose DIAGNOSTIC AND USAGE INFORMATION instead.

In the interest of privacy, I suggest that, before posting, you edit out the “Anonymous UUID,” a long string of letters, numbers, and dashes in the header of the report, if it’s present (it may not be.)

Please don’t post other kinds of diagnostic report—they're very long and rarely helpful.

When you post the log extract or the crash report, you might see an error message on the web page: "You have included content in your post that is not permitted," or "The message contains invalid characters." That's a bug in the forum software. Please post the text on Pastebin, then post a link here to the page you created.