“send as” an existing Mail Contact in Exchange 2010

Found out that it was what everyone was suggesting. When I made the Staff distribution list from a standard list to a dynamic list, something got messed up. I went into OWA, brought up the nickname cache (little pop-up menu when typing in the address in a new mail) and hit delete on the name, it removed it from the nickname cache. When they tried to send again, it sent to the correct list.

Thanks for everyone's help!

We've found a work-around in the meanwhile.

If we split up the accounts into 4 different accounts, and grant the correct permissions, we are able to send as any user.

However this is a very pale solution. this would multiply the number of accounts in both AD and Exchange

Still searching for a official fix on this.