Meeting invitations show up as regular email.

[Stever]

Outlook 2003 SP3 + all updates
Exchange server 2003 SP2 + all updates

When our users send out a meeting invitation to others in the company, most
of the invites show up as a regular email instead of the form that allows
the users to accept/decline the meeting invitation. For one of the users, of
15 sent only 8 of them went through correctly. This seems to be a recent
issue, could a office update be causing this?

Any ideas?

Thanks in advance

Steve