[Squawk 8888]

ou'd be surprised how many medium -> large sites don't have in-addrs for their outbound email relays

When I set up my mail server it took less than a day to discover the importance of IN-ARPA-ADDR registration. Most ISPs don't do a reverse lookup but a significant number of corporate mail systems do, which I found out after about 25% of the outbound traffic got hung up in my server.

[dfrussell]

It's useful to have, but by your own account 75% accepted email without an in-addr.

[Texas_Jarhead]

"Most ISPs don't do a reverse lookup but a significant number of corporate mail systems do, which I found out after about 25% of the outbound traffic got hung up in my server."

Yup, you're right. If you don't have that rDNS entry then as time goes by fewer and fewer messsages will be delivered.