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Sender Policy Framework (SPF)

Sender Policy Framework (SPF) is an anti spam approach in which the Internet domain of an email sender can be authenticated for that sender. It is designed to discourage spammers who routinely disguise the origin of their email--a practice known as email spoofing. SPF works to make it easier for a mail server to determine when a message comes from a domain other than the one claimed.

Using SPF, each participating domain declares attributes that uniquely describe their mail, including authorized senders. This description is represented in an SPF record, which is published in DNS (domain name system) records. An SPF client program is then used to query for the correct SPF record, in order to determine whether a message comes from an authorized source. Action taken on messages that fail the SPF test will depend on the receiving mail server.

In IceWarp Mail Server, support for SPF has been added within the SpamAssassin processor found in the Instant AntiSpam component. In short, a rule has been added that states if the SPF fails, then the SpamAssassin "score" is increased; the higher the score, the more likely the message is considered to be spam. IceWarp Mail Server administrators control the score thresholds and subsequent action. For example, administrators may stipulate that any message receiving a score of 3 or above be considered spam and automatically deleted.

Within IceWarp Mail Server, messages are not automatically deleted based solely on SPF results. Instead, these results are combined with other anti spam measures to determine the overall probability that a message is spam.

To learn more about SPF and how to publish SPF records for your own domains, please visit:

This site contains information on the configuration of SPF and an SPF Record Wizard that simplifies the process for you. Once you publish your own SPF records, then legitimate email sent from your domain will pass the SPF authentication test performed by receiving mail servers.
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