You could use a rule in Outlook but then the message in your comcast.net
mailbox will show up as a forwarded message from your morstan.com
mailbox, not as an original message that would've been sent directly to
your comcast.net mailbox.

Check if forwarding is a server-side option for your morstan.com
account.  That is, have the server forward the message.  It may leave
the headers intact.  It also doesn't require you to leave Outlook
running all the time to do the forwarding.