SPF is a way for Internet Service Providers to verify that a mail server (IP address) is authorized to send email for a specific domain.
To use SPF, the administrator of an email domain publishes a list of servers or IP addresses that are allowed to send email on behalf of the domain. When a sender tries to hand-off email to an email “receiving” sever for delivery, the email server checks to see if the sender is on domain’s list of allowed senders. If so, then a link has been established between the piece of email and the email domain.
SPF has become exceedingly important to help verify which sending infrastructure can send email on behalf of your domain, and directly impacts the deliverability. SPF validation requires specifying individual or ranges of IP addresses that are authorized to send email on your behalf. Use our Source Viewer within your account to see what sending sources need SPF inclusion.