[lug] sendmail from cable/dhcp

[Neal McBurnett]

First - a clarification.  My major puzzlement is why this is not a
more common issue.  It seems to me that anyone on a dhcp connection
using mailers like mutt, which rely on a local Unix MTA like sendmail,
would run into this problem.  It is not a problem for Mozilla, which
does the smtp by itself, but note that you have to configure Mozilla
to tell it your smtp server.

I.e. I see no hints in Redhat's mail documentation or bundled sendmail
config files and documentation about how to configure sendmail to pass
everything off to a specified smtp server.  I know I've found that
sort of thing in the past and can find it again, but how do most
people deal with this?

Granted that most recipients out there aren't as picky as
colorado.edu, but as others have said, this situation is just
getting worse due to spam.

My main goal is more ambitious - a config file that lets me normally
send directly, but to relay via mail.attbi.com for specified domains.

I've responded to specific questions below.

On Wed, Mar 26, 2003 at 11:07:45AM -0700, Bill Jorgensen wrote:
> On Tue, 25 Mar 2003, Neal McBurnett wrote:
> > For years I've had no trouble with a standard redhat configuration,
> > sending email via mutt and a local sendmail on my machine, directly to
> > the recipients.  The ISP is attbi, but I don't use their smtp server.
> > 
> > I.e. I'm on a dhcp connection.  But that connection hardly every
> > changes IP address because the machine is up all the time.
> 
> A question or two...
> 
> 1.) Before the issue were your email sent as neal at attbi.com? If it was
> not could you look at your mail header to see how sendmail is handling
> your mail?

I have always specified "From: neal at bcn.boulder.co.us" and have not
had problems with that despite the fact that my "From " envelope
header line lists neal at 12-253-85-111.client.attbi.com.

Look at the headers on this mail, e.g., for more details.

> 2.) I read Bear's response and it is important to know how attbi.com sees
> your box within their name space because that will dictate your MX records
> for email. Would you be able to get that information? For instance, I have
> a PC workstation at work that accesses the company network via DHCP. However,
> the NAME of my workstation stays the same within the name space regardless
> of IP address.

Attbi (now comcast I guess) doesn't offer permanent DNS addrs which
track your changing IP address, as far as I know.  Their tech support
suggested they didn't really even support dns for customer's machines,
or something like that.  But while talking to them I figured out that
I was using the wrong address in the first place, so I didn't pursue
that one....  There was one other time, 2002-03-09, when I got this
message, but it went away, and I figured it was just a DNS outage on
their part.  Could well be the same problem now.

And I agree with others who note that the *reverse dns* lookup is the
important one for many mail servers.  They see what IP you connect on,
and look to see if the reverse DNS lookup of that IP addr is the same
as what you claim in your "From " line.

Thanks,

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


> > Then I rebooted a few days ago, and now mail to certain places
> > (like colorado.edu) is not working.  I get bounces with this message
> > 
> >  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
> 
> I would investigate to see if attbi.com will define your hostname within
> their name space so that you do not care about what IP you have. The name of
> your box stays the same and you let attbi.com deal with the change of IP
> because of a reboot of your box. This may cost you though.
>
> >  1) Any insight on fixing this particular problem?  I'd like to send
> >  email directly because then I can look at the logs to see exactly
> >  when the mail was delivered to the recipient's machine, and I can
> >  turn on opportunistic encryption via SSL, and other useful features.
> 
> It has been a while since I have had the opportunity to trouble shoot
> email issues. Good luck. http://www.sendmail.org can be a wealth of
> information. You can post questions there too if you would like.
> 
> Later,
> 
> Bill