Mail continues to not quit

Please take these steps to delete the Mail "sandbox" folders.

Step 1

Back up all data.

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

~/Library/Containers/com.apple.mail

Right-click or control-click the highlighted line and select

Services ▹ Reveal

from the contextual menu.* A Finder window should open with a folder named "com.apple.mail" selected. If it does, move the selected folder—not just its contents—to the Desktop. Leave the Finder window open for now.

Restart the computer. Launch Mail and test. If the problem is resolved, you may have to recreate some of your Mail settings. Any custom stationery that you created may be lost. Ask for instructions if you want to preserve that data. You can then delete the folder you moved and close the Finder window.

Caution: If you change any of the contents of the sandbox, but leave the folder itself in place, Mail may crash or not launch at all. Deleting the whole sandbox will cause it to be rebuilt automatically.

Step 2

If Step 1 doesn't solve the problem, repeat with this line:

~/Library/Containers/com.apple.MailServiceAgent

*If you don't see the contextual menu item, copy the selected text to the Clipboard by pressing the key combination command-C. In the Finder, select

Go ▹ Go to Folder...

from the menu bar and paste into the box that opens by pressing command-V. You won't see what you pasted because a line break is included. Press return.

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.

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.

Click the Clear Display icon in the toolbar. Then try to quit Mail. Select any lines that appear in the Console window. 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 or email address, may appear in the log. Anonymize before posting.

When you post the log extract, 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.

In the settings for the Gmail account, uncheck the box marked Enable this account and see whether there's any change.

The question is whether Mail quits now.

And when you reenable the account, does Mail go back to not quitting?

By asking these questions.