spf vs sender callouts

Spf Vs Sender Callouts

The use of spf by mail providers is purely voluntary.
Right now, unfortunately, spf isn't in widespread-enough use to be viable as a spam-detection tool though it is beneficial in preventing bounces to innocent mail users whose addresses have been forged into the spam.
The sender policy framework (SPF) is a set of procedures that allows mail providers to exchange information in real time on who they permit to send mail and from which hosts.
orgSender policy framework, or SPF, is a sort of "patch" for internet e-mail systems that allows the operators of an internet domain to post which hosts are allowed — and which are not allowed — to send mail on behalf of their users and allows hosts receiving mail purporting to be from a given domain to look up the policies of this domain to determine whether the mail may be spoofed or illegitimate.
SPF can be thought of as a sort of reverse of the dig mx lookup, allowing receiving mail hosts to look up sending mail hosts for a domain, just as sending hosts can use dig mx to find the receiving hosts for a domain.
SPF (Sender Policy Framework) allows the owner of a domain to publishes an SPF record in the domain's DNS zone.
The SPF record specifies which mail servers are authorized to send email from that domain.
A receiving server can then check the domain's SPF record to see if the incoming email came from a valid server or not.