New to mac. I have two accounts in mail: a Yahoo Plus account (which has the usual flakiness) and an Outlook Exchange account. Both work reasonably well with intermittent loss of contact. Every time I wake the computer from sleep after several hours, mail begins to sync 3700 "incoming messages". Why? I can't tell which account is doing this, or both, or whether this is normal behavior. Have looked at preferences but can't figure out what to change, if anything. Just seemed to me that rather than downloading every message, it should just update the ones that have changed since the last time I accessed the account from this computer. But I'm sure I'm missing something.....