We are using exchange 2003 with google postini mail security for incoming mails. We have postini mail servers in the MX record with higher prefrence. For out going mails we are using our own smtp server. all is working well except some domains are not accepting mails from our domain, message bounced back with "#5.5.0 smtp;550-Verification failed " error. Our domain name is mabanisteel.com and the mail server host is mail.mabanisteel.com.
Please help as this issue becomes very critical for us.
Thanks in advance