Thanks for the info regarding Define Send/Receive groups. That's helpful.

As for the other issue, in order to forward a certain email address to a
Gmail account I had to delete it as an email address in order to forward it
to the Gmail account. So that address that I had set up as an email account
in Outlook didn't really exist anymore. I guess this is how it works. Not
sure. At any rate because that account was still trying to send/receive
(that's why I wanted to disable it, rather than delete it) Outlook got
"stuck" at that address and wouldn't process the other accounts.
Hopefully this makes some sense.