AOL, Microsoft (MSN, Hotmail and Windows Live Mail) and Comcast each shared details about their basic anti-spam efforts at the Authentication & Online Trust Association Summit in Boston in April. Silverpop's Director of Deliverability Ted Roberts was in attendance and brought back some valuable tips for marketers.

America Online
In the ongoing battle to spare customers an inbox full of spam, many ISPs provide a "this is spam" button. When a recipient clicks the button, the offending email is usually deleted and any additional mail from that sender is blocked. ISPs may also use these complaints to help identify senders whose entire mailings should be blocked. As a result, the complaints of a few can prevent a sender's messages from getting through to anyone.  Legitimate senders understandably would like to know when someone hits the spam button so that they  can prevent future complaints by removing that person from their list.

Unfortunately most major ISPs don't provide this information in a way that is easy to use. AOL is an exception. AOL offers a free feedback loop and will forward senders any email that a recipient reports as spam by using the AOL spam button.

• Set up a Feedback Loop
  AOL said the best way for senders to improve deliverability with the ISP is to set up a feedback loop in order to reduce the number of complaints it receives from recipients. AOL provides an easy-to-use feedback loop form at: http://postmaster.info.aol.com/tools/fbl.html 
• Get Authenticated
  AOL also said it plans to incorporate the Sender Policy Framework and DomainKeys Identified Mail authentication protocols into its reputation model in the coming months. By late summer it hopes to be actively using both protocols as a means of authentication and reputation checking for connecting IPs to help it determine whether a message will be delivered.

MSN, Hotmail and Windows Live Mail
Reputation is key to successful deliverability at Microsoft. When you send to these addresses, Microsoft relies heavily on IP and domain reputation and mailing history in order to determine whether to deliver your mail to the Inbox, Junk folder or Trash.

• Send Consistent (and Smaller) Volumes
  Because infrequent senders who send large volumes monthly or quarterly can be an indicator of a spammer, Microsoft said it's better to email smaller volumes more often rather than larger volumes at infrequent intervals. Consistent mailings of 5,000 – 10,000 emails per day have been documented as performing well.
• Get Authenticated
  Microsoft uses the Sender ID authentication protocol to verify an email sender's identity, and recommends that every sub-domain have its own SPF and Sender ID record.
• Don't Depend on the Address Book
  Unlike AOL, which allows senders to bypass some or all subsequent filters if their from-address is in the recipient's address book, Microsoft doesn't rely on the user's address book as a determining factor for email placement.The address book is referenced late in the filtering process, so email may be blocked by other filters first, even if the user has added the sender to their address book and safe-listed the domain.

Comcast
As the largest broadband provider in the United States, Comcast is an easy target for eager spammers. But permission-based marketers can take steps to improve their chances of delivery at this ISP.

• Get Authenticated
  Comcast said it will adopt DKIM as an extension of its reputation check by the end of 2007.
• Watch for a Feedback Loop in 2007
  Comcast said it plans to launch a feedback loop for spam complaints by the end of this year.

One Thing in Common
As ISPs continue to battle spam, authentication will become increasingly important. If you are not already authenticating with a combination of SPF, Sender ID and DKIM, now is the time. If you start now, you can be in good stead with the major ISPs by the holiday season. Whereas Microsoft espouses Sender ID, many others advocate a combination of SPF and DKIM or Sender ID and DKIM.

You can check with your email service provider about assisting you with your email authentication needs as well as facilitating the process of enlisting a reputation-certification service appropriate for your unique business situation.