Hi,
These are all governed by DNS in that:
- When an SMTP host (domino is an SMTP host when delivering to some other SMTP server) connets to another to send e-mail, the receivng server gets the IP adddress from the connection and queries it to resolve to a name. It might succeed or not. If not it can be isntructed to close the cunnestion with a 4.7.1 Relaying deined error or a 4.5.0 temprary error through its configuration settings.
If it resolves the name then it queries the DNS with the obtained FQDN from the reverse query. After it gets the name depending on its configuration it might reject the mail if DNS and Reverse DNS entries don't much. Then again it might not. Instead it might be configured to requery the DNS for an SPF TXT record. An SPF record is a test record and it returns configured E-mail forwarders for the domain it can whether be a catch-all record saying then any server is permitted t forward mail on its behalf or lists some servers which are authorized to deliver mail on the domains behalf. After this query , even if Reverse and forward DNS queries disagree the mail could be accepted.
As you see this is all DNS related. There are also several problems with reverse lookup zones:
- First of all reverse zones are not as flexible as forward zones which could be easily changed on registrar's page. They are assigned to ISP's and Reverse DNS could be set-up only on the intended server and contain full zone data only. Until recently it was a problem nad only resolved with some recent RFC's allowed for subnet delegation in Reverse DNS. For this reason they must be maintained mnually by ISP's and much of them don't care about it at all. I guess this is the case for your second DNS. I'll suggest you to both insist on to get it corrected by the ISP and also add an SPF record to your zone to prevent any further problems.
For further reference:
On SPF Records: http://www.openspf.org/
On Subnetting the Reverse DNS (classless in-addr.arpa delegation) http://www.faqs.org/rfcs/r
On Reverse DNS lookup: http://en.wikipedia.org/wi
On Reverse DNS Delegation practices: http://www.zytrax.com/book
I hope this helps.
Cheers,
K.
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by: fgrushevskyPosted on 2009-05-12 at 14:58:03ID: 24369890
It is "Fully qualified Internet host name" on the basic tab of the server document