Microsoft deployed Sender ID e-mail authentication alerts via a new "safety bar" in the Hotmail user interface to further protect e-mail users from malicious spam and scams. Emails sent to MSN and Hotmail addresses without authentication by Sender ID will now show a message warning recipients that the email could not be authenticated.

The warning message is the first step in a two-stage process to manage junk email. For the next few months, unauthenticated email messages will simply bear the warning. However, Microsoft warned that beginning around November 2005, MSN and Hotmail will begin to ship emails without Sender ID authentication directly to users’ junk folders.

The Sender ID Framework is an email authentication technology protocol that helps address the problem of spoofing and phishing by verifying the domain name from which email is sent. Sender ID validates the origin of email by verifying the IP address of the sender against the purported owner of the sending domain.

Read what Matt Blumberg, CEO of Return Path, thinks what it will (and won’t) do in his blog post titled: "Why We Love Email Authentication, But Why It Won’t Stop Spam".

In a quick FAQ – with open access until July 2nd – MarketingSherpa explains how this affects email marketers:

• What happens if your email doesn’t have Sender ID?
• Why you can’t count on your email vendor to handle everything for you?
• How Sender ID will affect deliverability?
• Why most junk mail won’t be stopped by Sender ID?

Plus, they’ve included a PDF of the most useful instructional booklet they’ve found on handling Sender ID.