Re: [exim] SMTP 550 user not authorized.

Bradley Walker wrote:

> Administrator" with the error message of "SMTP 550 - User not Authorized to
> send".

If you do not find that string in your Exim configuration file, then
your server did not generate that bounce.

Either a (transparent?) downstream server did this or your clients
connected to a completely different host (DNS/ARP glitches?).

/tom