Sender Policy Framework (SPF) is a method of fighting spam. As more time passes, this protocol will be used as one of the standard methods of fighting spam on the Internet. An SPF record is a TXT record that is part of a domain's DNS zone file. The TXT record specifies a list of authorized host names/IP addresses that mail can originate from for a given domain name. Once this entry is placed within the DNS zone, no further configuration is necessary to take advantage of servers that incorporate SPF checking into their anti-spam systems. This SPF record is added the same way as a regular A, MX, or CNAME record.
The authoritative source for this information can be found here: http://www.openspf.net/SPF_Record_Syntax.
Your domain must be using DNN4Less name servers:
- Log into Control Panel.
- Select your domain name
- Edit DNS Settings
- Click + Add a record to create a new record. Set the type to TXT and enter your SPF record in the right column.
- Click OK to Save the changes.