Sender Policy Framework (SPF) is a simple email validation system. It is designed to detect email spoofing by providing a mechanism, to allow receiving mail exchange to check that incoming mail from a domain is being sent from a host authorized by that domain's administrators. The list of authorized sending hosts for a domain is published in the Domain Name System (DNS) records for that domain in the form of a specially formatted TXT record. Email spam and phishing often use forged sender addresses, so publishing and checking SPF records can be considered anti-spam techniques.
If you are using SPF record in your environment, you need to authorize iSheriff to send emails on your behalf. To do so, please add the following in your existing SPF record: