What is Sender-ID ?

The Sender ID Framework is an e-mail authentication technology protocol that helps address the problem of spoofing and phishing by verifying the domain name from which e-mail is sent. Sender ID validates the origin of e-mail by verifying the IP address of the sender against the purported owner of the sending domain.

How does Sender ID Framework work?

• Sender sends an e-mail to Receiver.
• Receiver’s inbound e-mail server receives e-mail and calls its Sender ID Framework.
• The Sender ID Framework looks up the SPF record of the domain that Sender is using for sending the mail.
• The receiving Mail Transfer Agent (MTA) determines if the outbound Mail Server IP address matches IP addresses that are authorized to send mail for the user.

Find out more information regarding Sender-ID here

What is Sender Policy Framework - SPF

SPF fights return-path address forgery and makes it easier to identify spoofs.
Domain owners identify sending mail servers in DNS.
SMTP receivers verify the envelope sender address against this information, and can distinguish authentic messages from forgeries before any message data is transmitted.

How SPF works

In this example, Enterux.com is the sending domain, and yourdomain.com is the receiver.

Enterux has published SPF records, specifying which computers on the internet is able to send out email as someone@enterux.com, currently our SPF record says

v=spf1 a mx a:mailer1.myorderbox.com mx:mail.enterux.com ?all,

Which means machines, mailer1.myorderbox.com, mail.enterux.com and www.enterux.com are the valid hosts online to send emails as someone@enterux.com

So When a real Enterux.com user sends mail, yourdomain.com receives the message from an Enterux server.
2. yourdomain.com checks Enterux's SPF record, to make sure the server is allowed to send mail from Enterux.
3. The server is listed, so yourdomain.com gives the message a pass.
(Expensive content-based spam checks can be bypassed, saving resources on the receiver side.)

Now when a spammer forges mail from Enterux.com, yourdomain.com receives the messages from an outside server.
2. Yourdomain.com checks Enterux's SPF record.
3. The server is not listed, so Yourdomain.com gives the message a fail.
(Expensive content-based spam checks can be bypassed, saving resources on the receiver side.)

Find out more details regarding SPF over here

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