diff --git a/src/freedombone-base-email b/src/freedombone-base-email
index 74460735..90795b3c 100755
--- a/src/freedombone-base-email
+++ b/src/freedombone-base-email
@@ -298,6 +298,7 @@ function configure_email_onion {
       echo "  domains   = riseup.net";
       echo "  transport = onion_relay";
       echo "  headers_remove = Received:Message-ID:X-Mailer:User-Agent";
+      echo "  headers_add = Message-ID: <\${lc:\${sha1:\$message_id}}@\$sender_address_domain>";
       echo "  route_data = \${perl{onionLookup}{$RISEUP_EMAIL_ONION}}"
       echo "  no_more"; } > /etc/exim4/conf.d/router/049_exim4-config-riseup
 
@@ -306,6 +307,7 @@ function configure_email_onion {
       echo "  domains   = *.onion";
       echo "  transport = onion_relay";
       echo "  headers_remove = Received:Message-ID:X-Mailer:User-Agent";
+      echo "  headers_add = Message-ID: <\${lc:\${sha1:\$message_id}}@\$sender_address_domain>";
       echo "  route_data = \${perl{onionLookup}{\$domain}}"
       echo "  no_more"; } > /etc/exim4/conf.d/router/050_exim4-config-onionrelays