[lug] sendmail from cable/dhcp

[Neal McBurnett]

Success!

I tried the suggestion of John and others - giving up on a sender
hostname that checks out via reverse dns.  I had a hostname via
"dyndns.org" and put that in my /etc/hosts file:
   127.0.0.1       example.dyndns.org localhost.localdomain localhost

and did a `service sendmail restart` and ran "sendmail -q" and that at
least got the queued mail out.  No need for any sendmail.cf changes.
This still fits in with my theory that there is some sort of DNS
problem between attbi.com and colorado.edu.

dyndns.org has a nice, free service and they do have scripts for linux
that can update your dns address if dhcp changes it.

I'm still planning to try out the "mailertable" for two domains - one
of which is a very old sunos machine with a weird, incompatible smtp
server ("Connection reset by example.com"), and the other for umn.edu
which refuses cable and dial-up lines.

And I'll use that also if I run into any reverse-dns-checking servers
out there.  The one that I was thinking of like that turns out to not
do so - it was a different problem.  Sorry about that....

Many thanks,

Neal McBurnett                 http://bcn.boulder.co.us/~neal/
GPG/PGP signed and/or sealed mail encouraged.  Keyid: 2C9EBA60

On Wed, Mar 26, 2003 at 10:07:41AM -0700, John Hernandez wrote:
> On Tuesday 25 March 2003 10:58 pm, Neal McBurnett wrote:
> >  451 4.1.8 Domain of sender address neal at 12-253-85-111.client.attbi.com
> > does not resolve Warning: message still undelivered after 4 hours
> >  Will keep trying until message is 5 days old
> 
> As mentioned before, I don't think this error has anything to do with DHCP or 
> your /etc/hosts file.  To fix it, I think you simply need to use a resolvable 
> domain in your sender address, for example, neal at example.com.  If you use 
> sendmail, you can use the DOMAIN and/or MASQUERADE features to accomplish 
> this.  In this case, example.com should have an MX record that points to an A 
> record for your box.  Given that your box is subject to spontaneous address 
> changes, this should probably be maintained using a dynamic DNS service.
> 
> Beware that some paranoid mail servers will block inbound messages from 
> broadband and dialup networks.  Nothing you can do about that, but it doesn't 
> seem to be the case here.
>
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