Steve said:
I've been having a problem lately sending emails to AOL users, well,
not me, but our email server.
Our email server has 1 public IP, but hosts about 4 different domain
nammes. And we do run our own DSN server.
Is it possible to set up a rDNS entry for each of the domains that
points to the same public IP for the mail server, that will comply
with AOL's requirements that each domain have a rDNS entry?
PTRs are not domain specific, they are mail server/IP address specific.
It is likely that your reverse lookup is still owned by your ISP, since they
are the actual owners of your IP address.
You can have your ISP create a PTR record for your IP giving the name of
your mail server. You should only have one PTR for the IP and one host name
for it to point to, use that name e.g. mail.mydomain.com for the SMTP
server's HELO name, and regardless of the E-mail domain, and use THAT name
in the MX record for the mail server name. Do not use mail server alias
names in MX records.
Here are some examples:
mydomain.com MX mail.mydomain.com
myotherdomain.com MX mail.mydomain.com
anyotherdomain.com MX mail.mydomain.com
In this example the PTR will give mail.mydomain.com in the PTR lookup for
your mail server. Keep in mind, the PTR lookup is for the mail server's name
and IP address, it is not for the E-mail domain the mail server hosts.
As for the HELO name, configuring it would depend on that SMTP software you
are using.
I would also recommend adding a SPF record in each e-mail domain zone, some
DNS hosting providers don't have an interface for adding the SPF, but I'm
sure most will add the SPF for you. If you run the Wizard at
http://www.openspf.org/ it will give you an output of the data to be used in
your SPF. You can use the same SPF data for all e-mail domains if the same
mail servers host the e-mail.
