SPF (Sender Policy Framework) is a sender authentication method developed in order to ensure mail server's security by applying different anti-spoofing mechanisms. This mechanism consists in making a DNS request in order to determine whether the mail message comes from an authorized source, which is described in a SPF record, registered on the DNS. SPF records contain domain attributes that uniquely describe mail messages.
The query may have one of the following seven possible results:
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pass: meaning the message meets the domain's definition for legitimate messages;
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neutral
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none
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soft fail
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fail: meaning the message does not meet the domain's definition for legitimate messages;
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temp error
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permanent error
In case of a permanent error, Axigen rejects the mail message generating the respective error. If a temporary error is generated, the Axigen mail server returns an error message to the sending party. In all other cases the mail message is accepted.