I am having an interesting issue with email from our Exchange 2003 server. Not all but only a handful of emails are being delayed and undleliverable. I thought I had a rDNS issue and had my ISP ad the PTR record. I ran a report at DNSReport.com on our domain, postallogistics.com, and other than a couple warnings it tells me that I am good to go. The server is up to date with service packs, running symantec anti-virus. The only thing that has changed in the past few months is my T1 provider (SBC now). This issue has been going on for a couple weeks now. Just fixed the rDNS this week.