Hi a0J,
I have been using this method for days now on several users, testing SEND AS before we go live, so at least in my environment it works as described 100%. I can see your error popping up around the internet so something else must be wrong in your environment.
I would suggest you create a brand new user/mailbox and:
- Switch Outlook to online mode
- Go to the GAL, select the FROM contacts you would like to send as, right click and select add to contacts.
- Then go to Address book (in inbox), go to tools-options and under "when sending email, check these address lists first" select custom, remove the GAL and leave only the user's Outlook contacts in there. The last bit is important, as I observed
a case where a user had two accounts in Outlook (an Exchange one and a POP3 one), with two Contact folders, both set to be used as an address book and my trick was not working. I had to remove everything but the Exchange mailbox Contacts and Suggested Contacts
for it to work.
Again I would suggest you tried this with a "clean" user (mailbox, .nk2 cache file). Our goal is for Outlook to use the users contact whenever its trying to validate/lookup the FROM address/display name.
If it works with a brand new user, then you can begin troubleshooting why it doesn't work with an old one.