Apple Mailbox is Full
My Apple Mail keeps saying that my mailbox is 90%, 95%, 100% full. I have emptied the Trash and deleted everything I can but now it's blocking incoming messages. What can I do?
MacBook Pro 15", macOS 10.12
If you have a lot of emails in your inbox, try going to Mail/Mailbox/New Mailbox and create an On My Mac mailbox. Copy the emails there, quit/reopen Mail and test.
Try rebuilding the mailbox by selecting it and then going to Mail/Mailbox/Rebuild.
If that doesn't work, try re-indexing the mailboxes. This can take awhile if you have a lot of mail.
Reindex messages For El Capitan, try looking in V3. Sierra use V4. High Sierra use V5.
Reindex messages (2) See post by Linc Davis