[ale] Linux via mindspring to AOL -> blackhole

[Robbie Honerkamp]

> The reverse DNS lookup problem is one of the two I have encountered
> (besides mindspring occasionally changing their PPP packet sizes).
> 
> The other one is that my sendmail (and possibly yours) gets confused when
> it does a DNS lookup and use the A name rather than the MX.
> 
> The solution, since I don't actually want to telnet to aol.com, is to do
> 
> 	nslookup -type=any aol.com
> 
> to get a MX record ("mail exchanger") and put an entry in my /etc/hosts
> file with a MX record's IP and "aol.com".  This also seems to be a problem
> for bell south and a few others.

This doesn't scale well. The entire purpose of DNS is to avoid
having to have a mongo /etc/hosts file that can't be easily 
updated. 

The A records for aol.com don't point at mail servers.  Your mailer
should use the MX records instead (which _do_ point at valid mail servers).
If your sendmail doesn't recognize MX records then you need to 
ftp to ftp.sendmail.org, grab a new copy of sendmail and compile
it to do MX lookups. If you don't want to mess with sendmail, there are 
wonderful MTAs out there that work just fine as sendmail replacements
(such as Qmail- http://www.qmail.org/).

I've never seen this problem happen with a Linux machine running
a stock sendmail before, but Solaris 2.x releases until recently
did ship with a sendmail binary that wouldn't look at MX records.
A search of the system would turn up a sendmail.mx binary that
you could replace the provided sendmail binary with that would
do MX lookups. 

Adding IP addresses to your /etc/hosts file is a kludge that
will cause more problems that it solves in the long run. It's
also an immense waste of time.

Robbie