NO no no no no no no !!!
You do not put your 'email-addresses' in your whitelist, the whitelist is optional and is for "clients" that are authorized to send you emails with a "from:" address set to your domain ..
That won't work from our site, because we have people constantly travelling to different networks, while still sending mail from @psfc.mit.edu.
I should be able to automate the process of adding usernames to a the sendmail access list, at the same time that the cyrus mailboxes are created, so in THEORY it should work. We'll see! Thanks.
Mark