I have the 8.0.1-7 brightmail gateway, and I'm confused about how to implement something for a 3rd party supplier.

They have set up a service for us which sends email from our domain. It sends mail into our organisation as well as to our customers, the mail has to relay through our gateway so that when our customers receive the emails, their mail servers will not reject the mail because of a failed reverse-DNS lookup. So ..

• I've added their IP's to our SPF record (we use SPF to authenticate our own domain, to combat spam)
• I've added their IP's into reputation - good senders - local good sender IP's
• I've also added their IP's into Administration - Configuration - hostname - SMTP - "Accept outbound mail connections from the following IP addresses and domains"

I thought this should be enough ... ?

They are able to send mail in from our domain, to recipients within the organisation. But when they try to relay through us to an external recipient the smtp conversation ends after rcpt to:<blah@blah.com> with 554 Recipient Address Rejected.

I thought this might have something to do with LDAP lists and dropping invalid recipients, so I went into Protocols - Recipients - and set it to "Accept all recipients". It made no difference.

Can someone tell me what I need to do to allow an external server use our gateway as a smarthost?