SENDER ID or SPF is an email authentication technology, used to verify the email sender.

Today, spam blockers and email servers are using Sender ID to validate the origin of an email, helping to identify and filter spam, spoofing, phishing or other deceptive email practices.

PoliteMail users gain the delivery benefits of Sender ID, because PoliteMail utilizes your own authentic email server to transmit your list mailings and direct email campaigns.

Sender ID validates an email domain by comparing the IP address of the sender's email server (the sender's IP is contained in the email header) to the authorized email server IP (contained in an SPF/txt record within the Domain Name System (DNS)).

If you are an email sender, and want to improve email delivery from your authentic email server, then your IT or domain administrator would simply create a Sender Policy Framework (SPF) record and add it to the DNS records of your domain.

Sender ID is a Microsoft sponsored technology, and more information is available from the Microsoft web site: http://www.microsoft.com/mscorp/safety/technologies/senderid/default.mspx