On Jan 26, 2009, at 6:17 PM, Mark Andrews wrote:
Which just means you have not ever experienced the problems causes. MTA are not required to look up the addresses of all the mail exchangers in the MX RRset to process the MX RRset. MTA usually learn their name by gethostname() or similar and that name is not a CNAME or there is a misconfiguration.The fact that email still gets delivered in the presence of misconfigurations is good luck rather than good management.
100% right. I refuse MX's that are cnamed, and I get emails from customers asking what is up. What is strange, and I can not figure it out, is that the admins of the DNS/email server always tell me this is the first time they have heard of it.
Despite me pointing them to RFC on the matter, since it has worked in the past, they think it is my MTA that is wrong. I hate to budge on it, as this is a simple thing to understand and fix, but it seems many other email servers out there will run up and down a DNS server to find any address they can.
In the end, they almost always refuse to change their DNS, and I and up making a static route for them. They change the record later, and then it breaks.
I have never got why this is such a hard thing for email admins to get right, but it certainly causes me headaches. I personally wish CNAME's would just go away, keep them around, but just stop talking about them, then new to DNS users would not use them.
-- Scott _______________________________________________ bind-users mailing list bind-users@lists.isc.org https://lists.isc.org/mailman/listinfo/bind-users
