I am running the Apple Mail application (v 9.3) to manage four email accounts (including iCloud) on my MacBook Air and El Capitan (v 10.11.6). I often have to force quit, messages get stuck in the outbox, and I get this error message: "Connections to the server “p56-imap.mail.me.com” on the default ports timed out" and similar, depending on which account is hanging up. I find myself resorting to using webmail for each address individually, which seems the opposite of the intention of Apple Mail. I can't uninstall and reinstall, because Mail is integral to the Operating System. Please help!