On 14/03/2008, Vincent Stemen <vs1@???> wrote:
> On 2008-03-14, Matt <lm7812@???> wrote:
> >> IF you are doing sender-verify, you will have to expect that a
> >> significant number of sending hosts will not pass.
> >>
> >> Faulty 'vanilla' DNS entries aside, many will be in large ISP 'pools'
> >> where incoming/outgoing are separate, and may not be properly listed in
> >> DNS, or just not configured to respond as you wish they would.
> >>
> >> Others may treat your query as possible spambot probing and shut *you*
> >> out. Still others have delays or greylsting that will look like a fail
> >> in any reasonable time, hence drop the connection.
> >
> > Its not a sender-verify like that. I THINK all it does is make sure
> > the sending email adresses domain has an mx record. I did not add
> > this to my exim config its just been there for years.
>
>
> Actually, it does not just do a DNS check. Sender verify connects to
> domain of the senders address and initiates the first step in sending
> mail to make sure their server responds that the senders email address
> exists. It then disconnects without actually delivering any mail.
No, you're wrong. 'Sender verify' passes the sender address through
the configured routers and verifies that it would be routeable - part
of which will probably involve an MX lookup if the address would be
routed remotely.
Sender verify with the callout option does the dummy delivery attempt
you're referring to. The two things are different, and the difference
is important.
Start reading here...
http://www.exim.org/exim-html-current/doc/html/spec_html/ch40.html#SECTaddressverification
Peter
--
Peter Bowyer
Email: peter@???
