Outlook 2003: When user chooses 'reply to all' on SOME emails within sent items, his own address doe

[QH]

Bit of an obscure one here, but one of the junior managers in our
organisation forwards information from his sent items on a regular
basis to colleagues. He hits the reply to all button, and usually his
own email address is inserted among the recipients, but on certain
emails this does not happen. Why is this? He uses Outlook 2003 and
email is provided by an Exchange 2003 server. The problem appears to
be specific to certain emails.

QH