Authentication of the sender domain with SPF is a must if you want your emails to reach private Gmail accounts. Otherwise they will not be delivered by Google. How to fix this? We explain.
Tech writer Günter Born reports in his blog that Gmail, Google's email service, has only been accepting incoming emails with a valid SPF record since February of this year.
The Sender Policy Framework was originally developed as a security measure to prevent the alteration of the sender address (= spoofing). It is intended to prevent the sending of e-mails via non-legitimate mail servers. The recipient's mail server can use the SPF record to check whether an e-mail originates from an authorized mail server.
First, because it shows the recipient that the sender is legitimate; second, because it improves the sender's reputation and thus the deliverability of the mails; and third, because more and more e-mail providers require an SPF record.
The SPF record is set in the domain settings (DNS) of the sending domain. The administrator of your e-mail service can provide you with more information.
For more on SPF records, see: