scott there was a thread about supanet last week, and how they check the ehlo against PTR. in their case, it will not be possible to send them a email from a virtual host. correct?
----- Original Message ----- From: "R. Scott Perry" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Friday, October 10, 2003 5:46 PM Subject: Re: [IMail Forum] PTR record for a virtual IP > > >I know, previously, it was stated that the ptr record just has to exist, > >but doesn t really have to point back to the same hostname as the MX. > > Optimally, you would want your mailserver to HELO/EHLO with a host name > that matches the reverse DNS entry, that has an A record pointing back to > the mailserver. > > Next best is HELO/EHLO that is a hostname that has an A record pointing > back to the mailserver, and a reverse DNS entry that points to some other > hostname that has an A record that points back to the IP of the > mailserver. For example, "EHLO mail.secondary_host.com", with > mail.secondary_host.com resolving to the IP of the mailserver, and the IP > of the mailserver having a reverse DNS entry of "mail.primary_host.com" > (also pointing back to the same IP). > > The keys are that: > > [1] The IP you are sending from has a reverse DNS entry. This is most > important. > [2] The reverse DNS entry be a host that resolves back to the IP the > mailserver is sending from. Most mailservers that check reverse DNS > entries don't verify this, but it is best to have it set up this way (in > other words, why say you are a host that you are not?). > [3] The HELO/EHLO needs to resolve to the IP of the mailserver. Very few > mailservers check this, but it is required. > > >My ISP still has control over the reverse zone and getting the first PTR > >set up was like pulling teeth. > > That's not a problem. Just so long as the first PTR record works properly > (the hostname points back to the IP of the mailserver), you're fine. > > >Which really brings me to my next question. Can there even be 2 PTR's > >pointing to different host names? > > Technically, yes. However, there is no known advantage to having multiple > PTR records on an IP. > > -Scott > --- > Declude JunkMail: The advanced anti-spam solution for IMail mailservers. > Declude Virus: Catches known viruses and is the leader in mailserver > vulnerability detection. > Find out what you've been missing: Ask about our free 30-day evaluation. > > --- > [This E-mail was scanned for viruses by Declude Virus (http://www.declude.com)] > > > To Unsubscribe: http://www.ipswitch.com/support/mailing-lists.html > List Archive: http://www.mail-archive.com/imail_forum%40list.ipswitch.com/ > Knowledge Base/FAQ: http://www.ipswitch.com/support/IMail/ > To Unsubscribe: http://www.ipswitch.com/support/mailing-lists.html List Archive: http://www.mail-archive.com/imail_forum%40list.ipswitch.com/ Knowledge Base/FAQ: http://www.ipswitch.com/support/IMail/
