On Thu, 7 Mar 2002, Frank S. Bernhardt wrote:
> I'm no expert but I've seen something similar to this at one of my customers. It's the 501 message that looks
> familiar. In my customer's instance the isp holding their domain name didn't have the fully qualified domain
> name of the mail server setup as an A record.
>
> For example, the customer has 2 servers, X and Y with the domain name of DOMAIN.COM. In the dns hosts record
> they had X.DOMAIN.COM setup with an A record and a CNAME pointer for Y.
>
> Some of the emails they were sending from Y.DOMAIN.COM got bounced with the 501 eeror message. Once the isp
> setup Y.DOMAIN.COM as an A record, all was well.
For any _domain_ being used as an email address, there really should be
an _MX_ record, which should point the the _host name_ of the server
which should receve mail for it.
Eg if <postmaster@???> is desired to be used as an email
address, there should be:
Y.DOMAIN.COM MX 10 some-host-name-here
People confusing *domains* and *hostnames* is perhaps one of the most
common confusions regarding DNS. Yes, they look similar. In fact, a
given string could be either a hostname or a domain, or even both
(although this generally isn't recommended.)
The A records, while technically legal, are a legacy. Anyone with a clue
should use MX records.
>
> Of course also check out Roger Burton West's link to orbz. That's always a good place to get info.
>
> Hope this helps.
>
> snurt@??? wrote:
>
> > Hi All,
> >
> > Looks like my adsl proviuder has banned my ip from their smtp server.
> >
> > (which i still use now anad again) as I am open relay..
> >
> > This was news to me, so i quickly checked...
> > 501 test: sender address must contain a domain
> > 250 <test@???> is syntactically correct
> > 550 relaying to <test@???> prohibited by administrator
> >
> > Looks like im not open relay to me..or am I mistaken ?
> >
> > THe relaying prohibvited line happened after the rcpt to: but the mail
> > from: let me put anything in...
> >
> > Sigh
> >
> > This message sent via webmail
> >
> > Oh btw, using exim 3 not 4 :)
> >
> > --
> >
> > ## List details at http://www.exim.org/mailman/listinfo/exim-users Exim details at http://www.exim.org/ ##
>
> --
>
> Regards
>
> Frank S. Bernhardt
> b.c.s.i.
> 14 Halton Court
> Markham, ON.
> L3P 6R3
>
> 905-471-1691 Voice
> 905-471-3016 FAX
>
> frank@???
>
>
>
> --
>
> ## List details at http://www.exim.org/mailman/listinfo/exim-users Exim details at http://www.exim.org/ ##
>
>
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