DNS and PTR records

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Joined: Tue Sep 19, 2006 4:39 am

DNS and PTR records

Post by jingo » Tue Sep 19, 2006 5:37 am

I was just wondering that when sending mail, is it required for mail acceptance in some strictly rfc respecting servers to the sender to have a reverse dns for his "from" field (the @example.com) that points to some of the MX or other records in the senders main zone? I mean, I don't have any reverse for my domains because my isp won't/can't make me one and refuses to delegate it. I'm even required to relay my outgoing mail through their servers. Everything seems to be working though and I haven't discovered any problems with people getting my mail. I was reading somewhere that mailservers should have a reverse dns but I didn't quite understand it.. My reverse is something like user7438932473.provider.com and my MX setup is like this:
5 mail.myserver.com
10 backup.myserver.com
20 mail.rollernet.us
20 mail2.rollernet.us

Sorry if this doesn't make sense, and sorry for my bad english.. But thanks for the great free service anyway! (my first post)

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Post by RollerNetSupport » Tue Sep 19, 2006 8:45 am

Mail servers should have a valid IP to name lookup (PTR record). Basically, this means that if you do a lookup on "" you get "mail.rollernet.us". Many mail servers will refuse to accept connections from IP addresses that do not have a name associated with them, and some will go further to check that the name returned resolves back to the same IP address. (IP -> PTR -> A -> IP)

However, if you're relaying all of your mail out through your ISP's mail server, you probably won't encounter this, since it only applies to direct clients. Your mail server is only connecting to your ISP's mail servers, so it's your ISP's servers that will be subject to all the testing and rules, not yours.
Technical Support support@rollernet.us
Roller Network LLC

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