Wilfred wrote:

In my desire to make my original post as brief as possible, I think I
misspoke when I said that I wanted to "move all my outgoing messages
to a specific domain to a specified folder". What I really want to
do is to "save" all these new, outgoing messages to a specified
folder without having to go back and manually move them or run a rule
that will move them from the Sent Items folder to the specified
folder.

Exactly the question I answered.

Wouldn't disabling the "Save copies in Sent Items" option disable that
option for all messages I send?

Of course not, or I wouldn't have suggested it. Use an outgoing rule.
--
Brian Tillman