I'm using Outlook 2007 with Gmail. It works like this:

Emails sent to my personal email address "john@doe.net" are redirected to my
Gmail account "john.doe@gmail.com" and 'picked up' by Outlook - that works
fine.

But when I send emails from Outlook via Gmail, Outlook apparently puts my
Gmail address in the email as sender identification rather than my personal
email address, event though I have configured Outlook with my personal email
address both as the "Reply E-mail" and as my User Information email address.
As a consequence, the sender ID in emails sent via my Gmail account using
Outlook is:

John Doe [mailto:john.doe@gmail.com] On Behalf Of John Doe

Does anyone know how to configure Outlook to just put my personal email
address in the sender ID field instead of my Gmail address with a totally
meaningless "On behalf of..." extension?

- or is it a Gmail problem?

Best
Thomas