I have a SBS 2008 server which hosts two domains, primary.com and secondary.com. I have gone through the various tutorials and guides on how to set up two domains on Exchange 2007 and have completed all the steps except isolating the address lists and GAL because we want one address list. The MX and rDNS for the primary.com domain point to remote.primary.com and there is an A record for it and also an SPF record of (v=spf1 ip4:our IP address –all) only our IP sends mail for this domain. Our secondary.com domain has its MX record set to remote.primary.com and the same SPF record as the primary domain and can send and receive email as well. When I look at the header of an email sent from the secondary domain it says it was received from remote.primary.com and passes SPF checks and we route all mail through DNS and don’t use a smarthost.
My problem lies in sending to Gmail, amongst others, email from the primary domain get through fine, however, the secondary domain get seen as spam, this is the case with some other domains we try and send to as well. Neither domain nor our IP is on any blacklist that I can find.
Has anyone any ideas why this might be the case, any help will be gratefully received.