What is Sender Policy Framework (SPF)?

An SPF (Sender Policy Framework) record (defined in RFC 4408) is a record (more specifically, a TXT-record) within the DNS data of a domain. SPF aims to reduce spam. It validates the HELO command and the MAIL FROM address of the sending mail server (client).

The SPF mentions what IP addresses are authorized to send email from the domain name. For example, if someone wants to send an email from ...@copernica.com, the DNS-data of copernica.com need to state that this is authorized for the linked IP address. The receiving mail server checks the SPF as soon as the email is offered. If the IP address is not mentioned in the SPF record, the content of the email will not be collected.

Copernica will check your settings for each emailing and will warn you when the SPF record is not set correctly. Not every sender will do this check and you have to adjust the DNS-data yourself. As owner of a domain name, you can add an SPF record to your DNS-data. This enables you to indicate that the IP address of external party X has permission to send emailings from your domain name.