New Imac - running 10.10.5 sitting next to my mid 2010 mbp - running 10.10.5 I noticed this morning that I have the little exclamation mark next to mail and several overnight emails aren't there. The exclamation point says it can't connect with the mail server. The accounts are set up identical - imap, same port, ssl is checked, passwords are correct, etc. Tried manually syncing, tried quitting mail and restarting, nothing seemed to work. Ultimately I had to re-boot the imac, when it came back on, everything was fine and all the mail was there. I'm guessing once this goes to sleep it's somehow losing mail. It isn't a gmail mail account. Suggestions?