Re: [cobalt-users] [RAQ4] MX entries in DNS optional?

[flash22@xxxxxxx]

On Fri, 9 Mar 2001, Edwin Nouwen wrote:

> List,
> 
> Aside from making it work when it doesn't, is there any other reason why I
> should add MX entries to my DNS?

Some email programs (eg exim) can be configured to be paranoid and only
send/recv mail from hosts with MX & A records for the domain name (tho the
docs generally warn people there are dire consiquences to this)

rfc974 defines this btw, saying

It is possible that the list of MXs in the response to the query will
   be empty.  This is a special case.  If the list is empty, mailers
   should treat it as if it contained one RR, an MX RR with a preference
   value of 0, and a host name of REMOTE.

...if a domain fails to advertise any information...
   ...give it the benefit of the doubt and attempt
   delivery.

(Eg the to original domain name)

There is an unstated assumption here, namely that the domain name has an A
record , otherwise it's impossible to deliver mail to it.

Other than that, no, you don't *have to* have an MX as long as the default
vague behaviour is ok :)


gsh

ps: if you read this rfc note that all references to WKS in it are
obsoleted by a later rfc