Default account when replying to certain email address

[Joe Bento]

I experienced a problem last evening that is really confusing me. I
emailed a friend I had not corresponded with in some time. Outlook
2003 is refusing to use my default email account when replying to this
one email address.

I have five different email accounts set up for particular purposes,
and (e-mail address removed) (example) is set as default. Nearly everything I
send uses this address unless I specifically tell Outlook to do
otherwise. When I send email to one particular person, Outlook
insists in using an alternate account to send, regardless of telling
it otherwise.

I'm out of ideas of what to check. If anyone has any thoughts, they
are greatly appreciated.

Joe

 

[Mary]

Are you replying to this person's email that was sent to the wrong acct?
That's the only thing I can think of.

 

[Joe Bento]

No, the received email was sent to my default account. However, my
reply does not use default, even when deliberately chosen. This
particular individual in replying is the only one I've ever seen this
happen. I'm baffled.

Joe