Mailgate issue - "Could Not Load Valid User"

Hi, I’m trying to get mailgate and mail integration to work on my RT

When I issue the following command :

(echo Subject: test; echo; echo test) | rt-mailgate --queue General --url --action correspond

I get this error in my apache error log:

Could not record email: Could not load a valid user

I found a mailthread that indicated this could be caused by the queue not
allowing “Everyone” to create tickets. I set that option and it still gives
me the same error.

Any help would be greatly appreciated.