Yahoo! starts grey-listing
Published August 25, 2007 by Me
Yahoo! introduced an interesting system of mail filtering this week by introducing a grey-listing system to check that mail incoming to their servers is from ‘genuine’ mail servers, and not fake ones set up by Yahoo! introduced an interesting system of mail filtering this week by introducing a grey-listing system to check that mail incoming to their servers is from ‘genuine’ mail servers, and not fake ones set up by spammers using dynamic IPs etc.
It works in such a way that the first attempted mail delivery from an outside server gets bounced back to the sending mail server with a “try again later” message, and will then accept the mail on the next go around which (depending on your ISP’s mailserver retry settings) may be an hour or so later. It’s basically to test that your message has come from a REAL mail server, and not some hacker/spammer.
I guess that they’ve got to do something because of the ever increasing levels of spam hitting their servers.
You can read more about how Yahoo! “defer” mail, and other related information at the Yahoo! Postmaster page.
