This was built on the fly to describe to @lelutin how that stuff work,
on a pad with a electronic pen, live, and could use some love.

service/email.md

@@ -808,6 +808,13 @@ passed.
 Most of the code is glue code in Puppet, along with a small set of
 patches to ud-ldap which were sent (and mostly accepted) upstream.
 
+### Email password sync flow
+
+This horrid diagram describes the way email passwords are set from
+LDAP to the submission server:
+
+![](howto/service/email/submit-mail-password-sync-diagram.png)
+
 ## Services
 
 The "submission" port (587) was previously used in the documentation