1. Sender ID: An Overview for Registrars ICANN Vancouver December 1, 2005
Harry Katz
Program Manager
Technology Care & Safety
Microsoft Corp.

2. Why E-mail Authentication?
Dramatically reduce domain spoofing
Important step towards controlling spam and phishing
Improved filtering for receivers
Improved deliverability + brand & domain name protection for senders
Foundation for sender reputation

3. Sender ID/SPF Overview
Message transits one or more servers en route to receiver
Determine purported responsible address (PRA) or “Mail From” check
Look up sender’s SPF record in DNS
Compare to legitimate IPs in SPF record
Pass  neutral or positive score
Fail  neutral or negative score
Reputation added to score
Optional user interface (UI) to users
Complete Inventory of sending servers
Publish SPF record in DNS
User sends as normal

4. Hotmail Experience In production since Jan. ’05
~25% of inbound mail is covered by an SPF record
Sender ID verdict used as input into spam filtering decision
Warning message displayed on Fail and Softfail
Starting to use Sender ID to build domain reputation

5. How Registrars Can Help
Publish SPF records for your own domain
Allow domain owners to publish and manage SPF records
Publish default “non-sending” SPF records for parked domains
example.com IN TXT “v=spf1 –all”
Publish default SPF records for hosted domains
example.com IN TXT “v=spf1 include:hosted.myregistrar.com –all”
hosted.myregistrar.com IN TXT “v=spf1 mx ip4: /24 –all”
Link to resources

6. © 2005 Microsoft Corporation. All rights reserved.
This presentation is for informational purposes only. Microsoft makes no warranties, express or implied, in this summary.