Reverse Dns Question...is it really necessary or not?

[Jonathan de Boyne Pollard]

CN> if no reverse dns are setup for my domains, is it 
CN> possible that I may miss couple of emails? 

People apply reverse lookup checks (even though they don't actually gain 
them anything) on the addresses of SMTP Relay clients.  No-one with any 
sense applies a reverse lookup check on the address of an SMTP Relay 
*server*.  The mail sent *to* you is bouncing for other reasons.

Why not read the bounce messages ?  They often tell one exactly why mail 
is bouncing.  Why do you assume that the problem with mail delivery is 
caused by DNS services ?  Why do you find yourself with a problem with 
one thing (mail delivery in this case) but instead of telling us what 
your actual problem is you ask about something else entirely (reverse 
DNS lookup) instead ?  What *is* this obsession with chocolate-covered 
bananas ?

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CN> does the reverse dns have to be setup on
CN> the ISP server or on my dns server?

No.  It has to be set up on the _appropriate_ content DNS server(s), which
may not be either of those.  Also bear in mind that some superdomain
owners like to employ byzantine and unnecessary delegation schemes for 
reverse lookup domain names that break the features of several DNS server, 
DHCP server, and DHCP client softwares.

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