Knowledge base

This knowledge base is where you can find anything related to email security. Whether you are an administrator, developer or marketeer, if you work with email this is the knowledge you'll need to improve your email security.


The Sender Policy Framework (SPF) is the most basic email security method. With SPF you can publish a list of authorized sender who may use your domain name to send email.


DomainKeys Identified Mail (DKIM) is a method to cryptographically sign email. With the signature the receiver can validate that an email is authentic and the sender was allowed to send email for the domain.


Domain-based Message Authentication, Reporting and Conformance (DMARC) is an extension to SPF and DKIM and also allows monitoring. With DMARC the domain owner can publish a policy on how receivers should process email from the domain.


Mail Transfer Agent Strict Transport Security (MTA-STS) is an email security standard for secure delivery of email to your domain.

In this article we'll explain how MTA-STS works and why it is needed.


TLS Reporting (TLS-RPT) is a reporting standard that allows you to monitor the secure transport of email to a domain.

In this article we'll explain how TLS reporting works and how it is used.

Email address types explained

An email contains multiple addresses for both the sender and the intended receiver. Many different names are used for these addresses, which often leads to confusion.

In this article we'll explain the various addresses, how we call them and what they are used for

How to create a DKIM record with OpenSSL

If you are an email server administrator or a developer of software that needs to send email you can use this guide to learn how to create DKIM keys using the popular open source OpenSSL suite.