I'm using Outlook 2003. I am also having a similar problem with meeting
invites arriving from external partners not using our server. Regardless of
when the meeting is scheduled for, it populates in the calendar as starting
at the next closest half hour. Meeting invites sent by internal employees
appear correctly.

I already checked the time zones, and have had several test messages sent
from different people (from corporate email accounts and private ones like
hotmail,) all with the same result.

Thoughts?