Author: Marcin Krol Date: To: exim-users Subject: Re: [exim] Sender verify at extreme
Graeme Fowler napisał(a): > However, they can be extremely useful in cases such as hosting farms,
> dedicated server providers and colos where all the mail goes out through
> a smarthost - calling back to *your own network* to check whether or not
> a sender is valid is very useful indeed.
> The main reason we use sender verify with callouts is that it eliminates
a huge amount of spam, and what can be more abusive than spam (incl.
e-mail phishing and frauds)?
Spammers notoriously use someone else's domains and callout eliminates
fictitious addresses at real domains.
I work at hosting company, and not only I don't mind e-mail addresses at
our site being verified by call-outs, but in fact I would welcome more
of them: this reduces the chance that spammer or other fraudster sending
mail that has domain of one of my users in the SMTP envelope to the
server that uses sender verify w/callouts.
More than once I had bad blood caused between link providers, customers
who aren't experts at issues of combined e-mail/DNS/online fraud areas
(they think that sender address on envelope in e-mail actually means
something) and our company because some spammer or fraudster used e-mail
address belonging to one of our customers to send spam or fraud. Had the
servers that were spamming target used callouts to MX for that customer,
that spamming wouldn't have happened, and we would be very happy to be
"burdened" with that miniscule cost of verifying e-mail addresses of our
customers at our hosts.
