Email sent to Mail Enabled Lists is bounced back by Exchange

Whilst on a customer site when mail enabling a document library called TestDocs the SMTP address for the contact created in AD was coming up as for example TestDocs@MOSS02.vsa.domain (name of my MOSS Server). Mail sent to this library was bouncing back as Exchange was trying to send it through its default SMTP connector and to a smart host which of course could not relay for MOSS02.vsa.domain

To get around this, once the list or document library is mail enabled a SMTP connector needs to be created in Exchange System Manager that allows mail to be routed to the SharePoint server. To allow this list to receive mail from external users you need to assign it a second SMTP address for the mail domain.