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(1) (Stateful Packet Firewall) See stateful inspection.

(2) (Sender Policy Framework) An email authentication system that verifies that the message came from an authorized mail server. SPF is designed to detect messages from spammers and phishers who falsify the sender's IP address in the email header. SPF is an extension to the SMTP mail protocol.

SPF Records
The DNS system identifies the IP address of a receiving mail server with a line of text in the DNS database known as an MX record. DNS also supports a "reverse MX" record, which identifies the sending mail server and is used by SPF. When an email message is received, the mail server checks the SPF record in the DNS to see if it matches the actual IP address of the message. If it does, the email is considered valid. For more information, visit www.spf.pobox.com.

SPF Classic and PRA
There are two approaches to checking email messages via SPF. SPF Classic systems check only the envelope header, while Microsoft's Purported Responsible Address (PRA) method looks at the headers within the message. See Sender ID, Joe Job, spam, phishing, throwaway domain and SMTP.
References in periodicals archive ?
George Azar, chairman of Gulf Sotheby's International Realty, said: "Today is a pivotal moment for us bringing on board SPF Realty - a household name.
With a sunscreen having SPF 15,  you could stand in that same sun exposure for 15 minutes," Dr.
Coppertone Sport Stick SPF 50 and Coppertone WaterBABIES Pure & Simple Stick SPF 50.
Francisco-Pasion was a speaker at the launch of homegrown beauty brand Happy Skin's first sun care line, Catch The Sun, which consists of two products: the Brightening UV Gel Cream SPF 40 PA+++, and the On The Go Hydrating UV Mist SPF 35 PA+++.
Olay Total Effects 7-in-1 Anti-Ageing Day moisturiser SPF 30, PS19.
For those regular tanners who are light-sensitive, or have a history of skin cancer, the negligible difference in SPF levels could make a difference.
Our findings are troubling because consumers may not be getting the amount of SPF protection they think they're getting.
But bear in mind it's not the price that indicates the level of protection a product offers but the SPF and UVA ratings.
In 2013, SPF Precut Lumber hosted the first-ever Canadian lumber grading seminar ever held in the Gulf region.
The Spray Polyurethane Foam Alliance (SPFA) is the premiere organization representing contractors, manufacturers, and the complete value chain of SPF on safety, technical, educational, advocacy, promotional and other issues.
Consumer Reports decided to put those SPF claims to the test in its own labs.
On the other hand, SPF expectations for one-year inflation expectations were much more stable over 2012.