blocking address by account

Is there a way to block addresses specifically for an account?  For example, I would like to block aa@bb.com from account1 and allow aa@bb.com for account 2.

Hi, unfortunately this is not possible in eM Client, you can only block email addresses for all your accounts.
But you might find rules useful, just setup a rule that redirects your mail from aa@bb.com to your other account.

Hope this helps,
Paul.