diff --git a/4.1-Extensions.md b/4.1-Extensions.md
index bd1e66d..d9cc823 100644
--- a/4.1-Extensions.md
+++ b/4.1-Extensions.md
@@ -5,6 +5,7 @@
 | [Lightning](http://www.mozilla.org/projects/calendar/)                       | [Source](https://hg.mozilla.org/comm-central/file/tip/calendar)      | Calendars                                                                                                                                                                                                                                                                                                                                                                                                                                                 | Thunderbird v78+ integrates [Lightning](https://www.thunderbird.net/en-US/thunderbird/78.0/releasenotes/#note-32)                                                     |
 | [Markdown Here](https://markdown-here.com)                                   | [Source](https://github.com/adam-p/markdown-here)                    | Write pretty HTML emails sometimes                                                                                                                                                                                                                                                                                                                                                                                                                        |                                                                                                                                                                       |
 | [Enigmail](https://addons.thunderbird.net/addon/enigmail/)                   | [Source](https://www.enigmail.net/index.php/en/download/source-code) | PGP                                                                                                                                                                                                                                                                                                                                                                                                                                                       | Thunderbird v78+ includes [built-in encryption](https://support.mozilla.org/en-US/kb/openpgp-thunderbird-howto-and-faq)                                               |
+| [DKIM Verifier](https://addons.thunderbird.net/addon/dkim-verifier/)         | [Source](https://github.com/lieser/dkim_verifier)                    | Verify DKIM signatures                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                       |
 
 ### Alternative solution