diff --git a/sendmail/templates/sendmail.mc.erb b/sendmail/templates/sendmail.mc.erb
index fc4f261..f879a39 100644
--- a/sendmail/templates/sendmail.mc.erb
+++ b/sendmail/templates/sendmail.mc.erb
@@ -24,7 +24,7 @@ define(`confTO_IDENT', `0')dnl
 dnl #
 <% if @ssl_key and @ssl_cert -%>
 define(`confAUTH_OPTIONS', `A p y')dnl
-TRUST_AUTH_MECH(`<%= @sendmail_auth_mech.join(' ') %>')dnl
+TRUST_AUTH_MECH(`<%= @sendmail_auth_mech.find_all{|mech| mech != 'EXTERNAL'}.join(' ') %>')dnl
 define(`confAUTH_MECHANISMS', `<%= @sendmail_auth_mech.join(' ') %>')dnl
 <% else -%>
 define(`confAUTH_OPTIONS', `A')dnl