DNSAdapter contains a set of useful adapter classes that present a common set of return types and errors for DNS services. This adapter layer makes it simple to swap in different DNS providers and was written by Valimail.


Created and maintained by Valimail, Postshiftprovides an Amazon Redshift extension for ActiveRecord 5 (Rails 5) PostgreSQL adapter based off of the existing activerecord5-redshift-adapter.

Mailman ARC patch

Valimail built the Mailman ARC patch, which provides ARC functionality for Mailman 3. Mailman is one of the most widely deployed mailing list management software in the world.


Valimail maintains OpenDMARC and contributes code to support the evaluation and reporting of ARC. OpenDMARC is a community effort to develop and maintain an open source package for providing DMARC report generation and policy enforcement services.


OpenDKIM is maintained by Valimail. We contribute code to support the evaluation and reporting of ARC to this TDP software that supports 100’s of millions of mailboxes.


Valimail wrote this password policy enforcement extension for devise-gem, which is a flexible authentication solution for Rails based on Warden.


Coppertone, written and maintained by Valimail, provides a Sender Policy Framework (SPF) toolkit for Ruby and includes tools for parsing SPF DNS records, evaluating the result of SPF checks for received emails, and creating appropriate email headers from the SPF result.

Authentication Headers

Authentication Headers, written and maintained by Valimail, is a Python library for the generation of email authentication headers. The library can perform DKIM, SPF, DMARC, and ARC validation and generate and affix the corresponding headers.


Sympa is an electronic mailing list manager used to automate list management functions such as subscription, moderation and management of archives.