support.google.com/a/answer/2466563?hl=en

Once SPF and DKIM are in place, you configure DMARC by adding policies to your domain's DNS records in the form of TXT records (just like with SPF or ADSP).

dkimcore.org

DKIM Core is a way to attach a token (or tokens) to an email that tells the recipient who is responsible for the email (typically the token would represent the author of the email, the operator of the email service, or the owner of a mailing list, but ...

www.spfwizard.net/what-is-spf-record.html

An article on what Sender Policy Framework (SPF) is.

dmarcian.com/dmarc-what/

This is a simple article explaining what DMARC is for and how it works.

en.wikipedia.org/wiki/Sender_Policy_Framework

Sender Policy Framework (SPF) is a simple email-validation system designed to detect email spoofing by providing a mechanism to allow receiving mail exchangers to check that incoming mail from a domain comes from a host authorized by that domain's admi ...

www.hostingfixes.com/email/what-are-spf-records

SPF records (Sender Policy Framework) are DNS entries that you add to your domain name. They will specify which IP numbers are allowed to send emails from your domain name. If email is spoofed from another location (such as saying that it’s comin ...

msdn.microsoft.com/en-us/library/cc188656%28v=exchsrvcs.149%...

You use SPF records to ensure that destination e-mail systems trust messages sent from your domain. The SPF record is important because it ensures that all the messages from your domain appear to originate from the messaging servers that support the cl ...

www.digitalsanctuary.com/tech-blog/debian/setting-up-spf-sen...

A Guide to Setting Up SPF, SenderId, Domain Keys, and DKIM as spam prevention measures

support.sendgrid.com/hc/en-us/articles/200185168-SPF-Don-t-E...

Many people may not realize it, but the Sender Policy Framework (SPF) specification has a limit on the number of DNS lookups (10) required to fully resolve an SPF record. One typically quickly exceeds this limit through the reckless use of the include ...

yoast.com/dev-blog/email-reliability/

When you send email from your web server, email reliability is very important. Setting up your SPF record correctly helps tremendously!

www.port25.com/support/dmarc/

Phishing attacks continue to be one of the top Internet security threats, costing companies and individuals billions of dollars every year.  Over 100 million phishing messages get through spam filters everyday costing brands and estimated 70.2 bil ...

www.port25.com/support/authentication-center/dkim/

Recently the IETF DKIM Working Group concluded discussion pertaining to Email Authentication. For Email Authentication this was a major win as DKIM shows much promise to help ISPs better understand wher ...

vamsoft.com/support/tools/spf-syntax-validator

Helps creating SPF policies by validating the syntax of SPF policy data.

vamsoft.com/support/tools/spf-policy-tester

Test IP addresses against live or a directly entered SPF policy and get a detailed evaluation log of the test. Helps with troubleshooting.

otalliance.org/resources/spf-dmarc-record-validator

Tool to validate if SPF and DMARC records have been "published" in a domain's DNS zone file. The tool will query the DNS of the respective domains and present the records found. Up to 500 domains may be entered. Tools to validate SPF and DMARC records ...

www.seoconsultants.com/tools/spf/

What is 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 me ...