diff --git a/doc/contributing.texi b/doc/contributing.texi
index c089cfc95e..938c8bfdb1 100644
--- a/doc/contributing.texi
+++ b/doc/contributing.texi
@@ -2021,11 +2021,12 @@ a subject, if your patch is to be applied on a branch other than
 @code{master}, say @code{core-updates}, specify it in the subject like
 @samp{[PATCH core-updates] @dots{}}.
 
-You may use your email client or the @command{git send-email} command
-(@pxref{Sending a Patch Series}).  We prefer to get patches in plain
-text messages, either inline or as MIME attachments.  You are advised to
-pay attention if your email client changes anything like line breaks or
-indentation which could potentially break the patches.
+You may use your email client, the @command{git send-email} command
+(@pxref{Sending a Patch Series}) or the @command{mumi send-email}
+command (@pxref{Debbugs User Interfaces}).  We prefer to get patches in
+plain text messages, either inline or as MIME attachments.  You are
+advised to pay attention if your email client changes anything like line
+breaks or indentation which could potentially break the patches.
 
 Expect some delay when you submit your very first patch to
 @email{guix-patches@@gnu.org}. You have to wait until you get an