Re: [LUG] Sendmail oddities

[Simon Waters <Simon@xxxxxxxxxxxxxxxxxxxx>]

Alex Stanley wrote:
> I'm having problems sending mail through a relay.
>
> - The relay's set up to accept mail from the IP of the Linux box
>
> - I can telnet to port 25 of the mail relay from the Linux box.  
>
> - I can resolve the name of the relay on the Linux box using nslookup.
>
> But, when the Linux box tries to send mail I get (addresses changed to protect 
> the guilty ;)) :
>
> Feb  3 10:55:10 rottcodd sendmail[8471]: i13AtAl08468: to=user@xxxxxxxxxxxxxxx, 
> ctladdr=root (0/0), delay=00:00:00, xdelay=00:00:00, mailer=relay, pri=60055, 
> relay='mailrelay.domain.com', dsn=5.1.2, stat=Host unknown (Name 
> server: 'mailrelay.domain.com': host not found)
> Feb  3 10:55:10 rottcodd sendmail[8471]: i13AtAl08468: i13AtAk08471: DSN: Host 
> unknown (Name server: 'mailrelay.domain.com': host not found)
> Feb  3 10:55:10 rottcodd sendmail[8471]: i13AtAk08471: to=root, delay=00:00:00, 
> xdelay=00:00:00, mailer=local, pri=30155, dsn=2.0.0, stat=Sent
>
> Can anyone help?

It's smells like a DNS problem of some kind, but without the domain
name, all I can do is suggest the domain is probably broken.

Is the relay name in the DNS "dig mailrelay.domain.com A" (I think
sendmail can ignore /etc/hosts for certain things although I try never
to know too much about sendmai). What about trying this for each name
server for that domain see if they give different answers "dig @a.b.c.d
mailrelay.domain.com A".

Also stop using nslookup - it is a pile of pants. Try ping to find how a
host resolves, and dig to find out what the DNS has.

Indeed if your nslookup doesn't say not to use it, everytime you try, it
is appallingly out of date.

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