Using SPF helps to validate outbound email sent from your company domain.
In order to use a custom domain, Office 365 requires that you add a SPF, TXT record to your DNS record to help prevent spoofing. SPF identifies which mail servers are allowed to send mail on your behalf.
Basically, SPF, along with DKIM, DMARC, and other technologies supported by Office 365 help prevent spoofing and phishing.
SPF is added as a TXT record that is used by DNS to identify which mail servers can send mail on behalf of your custom domain.
Recipient mail systems refer to the SPF, TXT record to determine whether a message from your custom domain comes from an authorized messaging server.
For example, let’s say that your custom domain fgsservices.co.uk uses Office 365. You add an SPF TXT record that lists the Office 365 messaging servers as legitimate mail servers for your domain.
When the receiving messaging server gets a message from firstname.lastname@example.org, the server looks up the SPF TXT record for fgsservices.co.uk and finds out whether the message is valid. If the receiving server finds out that the message comes from a server other than the Office 365 messaging servers listed in the SPF record, the receiving mail server can choose to reject the message as spam.
Also, if your custom domain does not have an SPF TXT record, some receiving servers may reject the message outright. This is because the receiving server cannot validate that the message comes from an authorized messaging server.
Tel: 01274 973600 or email email@example.com