diff --git a/requirements.txt b/requirements.txt
index 7755c3e..5444147 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -31,8 +31,11 @@ bcrypt
 # credit card storage and processing.
 stripe
 
-# DKIM Signed Email from Python.
+# DKIM Signed Email from Python, lot's of extras in here like async.
+# https://git.launchpad.net/dkimpy/tree/setup.py#n84
 dkimpy
+# needed for signing with ed25519 keys.
+dkimpy[ed25519]
 
 # MarkDown is a popular and familair WYSIWYM markup language.
 # python 3.