resolving email addresses

[James D. Parra]

Okay, did the 'nslookup -t=MX realdomain'
and received a series of Non-Authoritative responses and also used your
recommendation and received multiple Authoritative answers.

It appears the reverse lookup is working.  I wonder what is happening with
sendmail?

Also, I looked for Julian's suggestion to turn off
'FEATURE(`relay_based_on_MX')dnl' at sendmail.org, but I couldn't find
anything. If I remove this feature would anything else be lost?

Thank you.

James


-----Original Message-----
From: Derek Winkler [mailto:dwinkler at ALGORITHMICS.COM]
Sent: Tuesday, March 23, 2004 12:08 PM
To: MAILSCANNER at JISCMAIL.AC.UK
Subject: Re: resolving email addresses


This is what I'm thinking of, you're not using this...

accept_unresolvable_domains:

Normally, MAIL FROM: commands in the SMTP session will be refused if the
host part of the argument to MAIL FROM: cannot be located in the host name
service (e.g., an A or MX record in DNS). If you are inside a firewall that
has only a limited view of the Internet host name space, this could cause
problems. In this case you probably want to use this feature to accept all
domains on input, even if they are unresolvable.

Use nslookup...

# nslookup
Default Server:  localhost
Address:  127.0.0.1

> set type=MX
> realdomain.com
Server:  localhost
Address:  127.0.0.1

Non-authoritative answer:
realdomain.com  preference = 10, mail exchanger = mail.realdomain.com

Authoritative answers can be found from:
mail.realdomain.com     internet address = 192.216.19.101
>

Make sure you do it from the server.

> -----Original Message-----
> From: MailScanner mailing list [mailto:MAILSCANNER at JISCMAIL.AC.UK]On
> Behalf Of James D. Parra
> Sent: Tuesday, March 23, 2004 2:56 PM
> To: MAILSCANNER at JISCMAIL.AC.UK
> Subject: Re: resolving email addresses
>
>
> Thanks Derek,
>
> How would I have the server find the MX records?
>
>
> This is the forth MailScanner I built and previous three
> didn't have that
> error. Interesting though. I do see the Feature setting, I
> think. Is this
> it?
> FEATURE(`relay_based_on_MX')dnl
>
> Thanks again for your help.
>
> James
>
>
> -----Original Message-----
> From: Derek Winkler [mailto:dwinkler at ALGORITHMICS.COM]
> Sent: Tuesday, March 23, 2004 11:40 AM
> To: MAILSCANNER at JISCMAIL.AC.UK
> Subject: Re: resolving email addresses
>
>
> > Hello,
> >
> > I tried to test a new MailScanner/Sendmail setup we have,
> but from the
> > outside a telnet session to the mail server will give an
> > error of, "Domain
> > of sender address "joesomebody at realdomain.com" doesn't
> > resolve. However, I
> > can ping the domain from the server.
> >
> > Any clues on how to fix this?
>
> You may have a feature of sendmail turned on which doesn't
> accept email from
> addresses which don't have MX records.
>
> Can the server find MX records for the domain?
>
> >
> > Thank you in advance.
> >
> > James
> >
>