On Thursday 20 March 2008, David Koski wrote:
> On Wednesday 19 March 2008 22:53, MacShane, Tracy wrote:
> > > -----Original Message-----
> > >
> > > From: [email protected]
> > > [mailto:[email protected]] On Behalf Of David Koski
> > > Sent: Thursday, 20 March 2008 2:48 PM
> > > To: [email protected]
> > > Subject: smtp relay and smtp verification
> > >
> > > Hello,
> > >
> > > I have some Postfix blacklisting relay servers that I want to
> > > use smtp to verify recipients before accepting emails. For
> > > example, before accepting a message to [email protected] I
> > > want to verify that such an account exists using smtp to the
> > > MX at example.com. Can this be done with Postfix and how, if so?
> >
> > http://www.postfix.org/ADDRESS_VERIFICATION_README.html
>
> I think this is what I was looking for. Thanks!
>
> > This should be used as little as possible, IMO, for specific domains you
> > have trouble with. You're doubling up on network traffic with each
> > request you make, and you're naturally increasing the work the sending
> > server has to do. We find we get decent results blocking spurious mail
> > using the usual kinds of checks, a decent RBL and a content scanner.
>
> This is for incoming email only.
I did some testing with this in main.cf:
smtpd_recipient_restrictions =
...
check_recipient_access hash:/etc/postfix/recipient_access
recipient_access:
mytestdomain.com reject_unverified_recipient
kosmosisland.com reject_unverified_recipient
This host relays directly to kosmosisland.com but there is another hop to
mytestdomain.com, a Barracuda spam firewall. Mail to domain kosmosisland.com
is relayed as expected but mail to mytestdomain.com is rejected regardless of
wheather the email address is correct:
450 4.1.1 <[email protected]>: Recipient address rejected: undeliverable
address: host cuda2.myrelayhost.com[65.183.202.16] said: 550 Blocked (in
reply to RCPT TO command)
Is it not permitted to use recipient verification through a relay server?
Regards,
David Koski
[email protected]
