Hi Tim,
> Does your web hosting company also handle your
e-mail? If so, what's the problem?
Yes, I do have several email boxes with the web
hosting company, and several at various other iSP's.
> I suspect you may be making the seemingly common but
puzzling (to me) mistake of thinking that because you
can telnet into an MX server for your domain (or set
that server as your mail gateway in an e-mail client)
and send e-mail, this is in some way an open relay.
How can it be?
I may be getting relaying and possible spam abuse,
mixed up. For example, I tested another domain (one I
manage), used it as the domain for telnet, used it as
the "RCPT TO: , but made up some bogus username@domain
for the "MAIL FROM:, ........ it got through, so that
would imply, to me at least, that anyone can use
_that_ domain to send spam. Yes, all the spam will go
to _that_ domain though. :)
> If the remote server *didn't* accept a telnet
session where you send mail (except on the basis of a
dialup DNSBL or something), how would it ever actually
handle mail for you? How would *any* mail to you
actually be accepted? Remember that SMTP is SMTP;
there is no conceptual difference between "SMTP
between two MTAs", "SMTP where one end is using a
telnet client" and "SMTP where one end is using an MUA
with smarthost set to the other end".
This isn't so much mail "TO" me, but mail I'm able to
send "THROUGH" my domain, without any authentication
at all.
> In summary: a server is only an open relay if you
can send mail through it, unauthenticated, to
*arbitrary* domains (i.e. not a domain which it is set
up to handle). Try sending to foo@??? and see
if it lets you do that. If it does, it's an open
relay. If it doesn't, it's probably not.
I just logged in (Telnet) to 'domain1', used that
domain as the "MAIL FROM", and I was able to send an
email to two other domains. No authentication was used
at all. What does that mean ?
> My concern is that, if I can do it, so can ANYONE
Er, don't you want "anyone" to be able to send you
mail?
This isn't mail "TO" me, it is mail THROUGH my domain.
Peter
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