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Are PTR Records Important?
erfmuffin asks: "I work for a medium-sized regional ISP. Recently we configured our email gateway to refuse connections to IP addresses that do not resolve (ie no reverse DNS). I am amazed at how many legitimate domains use mail servers with no PTR record! At the same time, we have avoided a great deal of junk mail in one swoop. Wouldn't it be better for mankind if all mail servers refused mail from non-resolvable IPs? Should all legitimate mail servers have valid PTR records or has the world become too lazy to make email delivery, easier?"
I host maybe 7 domains, an email server, and several other things from my dynamic-ip DSL connection. Have been maintaining it for over a year with reasonable uptimes. I cant have PTR records or reverse resolution to my domain... but I dont send spam.
Many cottage-industry websites will be closed and not everyone can afford professional hosting services that use Jboss, postgresql, php4, ldap etc. Least fan sites that can make no money, and homepages.
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The fact that mail systems that require PTR records before accepting mail significantly reduces spam is reason enough that PTR records should be required.
Hang on a second, I'm dizzy. Woo. That's one hell of a circular argument you've got there. I'm still trying to sort it out, but it seems like you might have actually made two full circuits of the argument in that one sentence. Wow.
The implicit assumption behind all of that, though, is that stopping some spam is more important than delivering all legitimate mail. You say so yourself: "I too experience a great deal of mail problems due to a lack of PTR records but, it is worth the effort to stick to this policy." That's completely wrongheaded. Mail should be delivered. That's what it's for. Given the choice between receiving no spam and missing the occasional important email and receiving all spam and getting all my important emails, I would choose the latter any day of the week. And so would most reasonable people, I think. The inconvenience and annoyance of hitting that "delete" key every day is nothing compared to the inconvenience and annoyance of not being able to receive email from a friend or business associate.
The same was once thought of having open relays, too. See how we changed out behavior with those?
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