Hi guys,

my emails to aol.com users are being dropped and after reading their faq, I realise it could be because my mail server do not have a reverse dns - which I need to get my ISP (who provides me with my IP addresses) to set up.


Getting them to setup is easy - just fill a form - but would that mean anything for my email server operations? Do I need to configure extra things to ensure the new reverse dns settings don backfire on me and cause all mails to my server to not reach its destination... or is it really just a configuration of the reverse dns and that's it?

Thanks!

i don't think that's the most likely reason. in my experience it's more commonly due to coming from a dynamic ip address. instead of using a local smtp server to send them out directly, your ISP will most likley have a relay you can use, e.g. smtp.yourisp.com, which will then be accepted by AOL.

As far as the lookup config itself, it's a one way thing, so there's no danger of it affecting anything else if it's working fine without a PTR for you IP address at present.

i deal with dns and smtp everyday. can you browse the internet from your MTA (or do you know for sure what IP is seen as the src IP when your MTA sends out email)? if so goto www.whatismyip.com, whatever IP it says your MTA is is the IP that should have a PTR record for. sometimes this does not always match your MX records, but thats ok as long as DNS is clean and makes sense.

your MTA's helo message will claim to be some host. i always make sure that it claims to be a valid fqdn that has proper A record in dns. PTR and A record dont really have to match (but should), they just need to be resolvable.

you should not need to make any changes to your MTA (other than making sure the helo claims to be a valid fqdn, also run a domain test from dnsstuff.com to see), and, your MTA should work with no issues delivering emails.

hi there... so accessing the site using my mail server, I got the IP. So I should use that IP for my PTR, when I submit application to my ISP yah>

and what is MTA?

and for the reverse dns... if my mail server's address is 'mail.domain.com' and my MX records point to 'domain.com', does it matter?

I just need to apply a PTR to both mail.domain.com and 'domain.com' via my ISP. right?

In most cases you need a static IP, reverse DNS to the domain you are sending from and in some cases domain keys for your domain. It's probably less hassle to just get your server to send thru your ISP's SMTP server.

MTA = mail transfer agent

to make it easy, use a 'A' record for 'MX', so make your MX "mail"
next, have your ISP host a PTR record for your MTA's IP, point it to "mail.domain.com"
next, make sure your MTA does a HELO with a fqdn of "mail.domain.com"

you dont need two PTR records, just have a PTR that matches the MTA HELO and it should match the src IP address the MTA uses on the internt. i however always populate my reverse zone so that any IP in my subnet that is queried for PTR there will be an answer. for unused IP's i just use a generic name like w.x.y.z.domain.com (wxyz of course being the IP for the PTR query).

this should remedy any/all issues with other MTA's doing checks on your MTA when your MTA sends email.

you should also ask your ISP about SPF records (http://www.openspf.org/).