All accounts keep going off line, quitting Mail fixes the issue.
I have 3 Gmail, 1 hotmail and a yahoo. Al go off line with a little alert symbol next to them.
If I select take all accounts on line nothing happens.
Email delivery stops.
To fix this, I quit Mail and re launch it. That fixes it.
It's realy annoying.
I have the same problem - it started when I upgraded to OS X 10.8
I thought subsequent releases may help, but I'm now on 10.8.2 and no joy.
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