Mail app won't open

An archived Apple Support document offered the following helpful suggestions:

If Mail unexpectedly quits when viewing certain messages

Mail may unexpectedly quit when displaying a message that is malformed or damaged. 

Mail may quit when you view an email message that is malformed or damaged, and it may continue to quit as long as the message remains selected. Resolve the issue by following these steps to delete the message:



1. Open Mail and immediately hold the Shift key until Mail opens. This causes Mail to open without any message or mailbox selected.
2. Hide the message viewer portion of the window by carefully dragging the thin separator bar between it and your list of messages. Keep dragging until Mail shows only the list of messages, not the message viewer. In this view, you can see messages only by double-clicking to open the message.
3. Click the affected message once to select it without opening it. Then press Delete or choose Message > Move to > Trash. 

Of course it may be tedious to determine which email message is causing the problem.

Another way to dispose of any problematic email message(s) is to use your email service provider's webmail interface, assuming it offers one.

For reference:

MAIL QUITTING UPON LAUNCH - Apple Community

Mail quits immediately on launching - Apple Community

Startup in Safe Mode and see if Mail will open.

see > Start up your Mac in safe mode - Apple Support

Then restart normally and see if Mail will now open up.

Having the same issue. Frustrating. Never happened before. Please help.

Drisee,

Please follow the directions already posted!