When I try to fetch incoming mail, I get 'Mailbox is not accessible : "Unknown error occurred.". In the meantime, mails will not be fetched in the mail fetching schedule.'

I get the same 'Unknown error occurred' when I send Outgoing mail as well.

This seems to be sporadic as it came back last night for a few hours. However, this morning (again after tickets came in overnight) it crapped out again and won't send or receive.

The error code is useless and the 'Troubleshoot' link is equally useless. The settings are not changing, but the service is.

Any help is appreciated.