Own mail server and reverse DNS with Uverse
I am getting conflicting information from AT&T and so I’d like to run this by the forum to see what insight I can get.
For many years, previously on DSL in CA and now on UVerse in IL, we have run our own mail server which covers 5 domains using an internal RHEL box (rhserver). All of the domains have an MX record which points to the WAN address of the router (now a 2 Wire 3801HGV) and the router has a pinhole defined to route port 25 traffic to rhserver. Works fine except…
We recently posted some queries on Craigslist and trying to respond to some of the responses we found that Craigslist has implemented a policy such that they block mail from address which return a “generic” response to a reverse DNS. Among the criteria which defines “generic” is containing an IP address. Since the IP for the router belongs to AT&T’s space, the standard response does contain the IP.
AT&T tells me they can’t assign my domain to be the reverse DNS for the router address because the router address is obtained via DHCP and could therefore change. I have been told, but so far am unable to confirm from AT&T, that the address returned by DHCP comes from a table linked by the MAC address of the router. I.e., the address won’t change unless the router changes or someone fiddles with the table. If this is true, I see no reason why they can’t apply the reverse DNS to that address and simply change it when and if something changes.
In pursuing this with AT&T lately, it was suggested that I use the sticky static IPs and make one of those the address for mail so that reverse DNS could be applied to that. My attempt to experiment with this resulted in no mail coming through and a port scan shows port 25 being blocked, which would seem to explain that, although AT&T claims that port 25 is not blocked.
Assuming I could get past this blockage, I also wonder if it is going to help. Is that sticky static going to be used for *outgoing* mail or will the mail continue to appear to come from the WAN address of the router? If the latter, then the reverse DNS on the sticky static will do no good. We do have the sticky static defined now in Add Additional Network, so if that is what is supposed to change the origin IP, it isn’t currently working.