Sender ID info
Ewan ...
We got asked a few questions today about Sender ID and Sender/Connection filtering in Exchange 2003. There have been some changes in how Exchange 2003 SP2 handles inbound email - specifically around filtering out bogus connections which come from servers that are either sending junk mail, or are unwittingly functioning as open relays for other miscreants to route junk mail through.
Sender ID is relatively simple technology, but it seems to cause confusion - think of it as a way of simply having a mechanism to validate that the server which it submitting the email to your environment is genuine, and has some responsibility to send mail on behalf of the domain that the sending user belongs to.
Sender ID technology grew out of an initiative which was akin to Caller ID - just like, if your phone supports Caller ID, you get to see the number of a caller before you pick up the phone, and if that is someone you know, you might be more likely to pick up the call than if it's a number you can't verify.
If you have Exchange 2003 SP2 running on any SMTP hosts in your organisation, you can enable Sender ID checking on inbound mail, but even if you don't, you can publish a record of all your SMTP servers in your own DNS, so that if someone receives mail from you and they choose to enable Sender ID checking, then they will be able to positively identify your mail and may be less likely to filter it as junk mail.
More info on Sender ID - http://www.microsoft.com/senderid
How to configure your DNS with an SPF record to identify your hosts - http://www.anti-spamtools.org
That's one Unplugged under our belts - only 9 more to go!
-- Ewan
More info on S
