diff --git a/gen-pmg.conf.5-opts.pl b/gen-pmg.conf.5-opts.pl
index 4ed3300..3237060 100755
--- a/gen-pmg.conf.5-opts.pl
+++ b/gen-pmg.conf.5-opts.pl
@@ -56,6 +56,7 @@ my $key_groups = {
 	    relay => 1,
 	    relaynomx => 1,
 	    relayport => 1,
+		relayprotocol => 1,
 	    smarthost => 1,
 	    smarthostport => 1,
 	}],
diff --git a/pmg.mail-relaying-conf-opts.adoc b/pmg.mail-relaying-conf-opts.adoc
index d76fa2b..917bddd 100644
--- a/pmg.mail-relaying-conf-opts.adoc
+++ b/pmg.mail-relaying-conf-opts.adoc
@@ -4,11 +4,16 @@ The default mail delivery transport (incoming mails).
 
 `relaynomx`: `<boolean>` ('default =' `0`)::
 
-Disable MX lookups for default relay.
+Disable MX lookups for default smtp relay.
+Will be ignored when choosing lmtp as transport protocol.
 
 `relayport`: `<integer> (1 - 65535)` ('default =' `25`)::
 
-SMTP port number for relay host.
+SMTP/LMTP port number for relay host.
+
+`relayprotocol`: `<smtp | lmtp>` ('default =' `smtp`)::
+
+Transport protocol for relay host.
 
 `smarthost`: `<string>` ::
 
diff --git a/pmgconfig.adoc b/pmgconfig.adoc
index d9b15dc..e6ebe57 100644
--- a/pmgconfig.adoc
+++ b/pmgconfig.adoc
@@ -371,8 +371,10 @@ e-mail servers. For example you can send e-mails addressed to
 domain.com to your first e-mail server, and e-mails addressed to
 subdomain.domain.com to a second one.
 
-You can add the IP addresses, hostname and SMTP ports and mail domains (or
-just single email addresses) of your additional e-mail servers.
+You can add the IP addresses, hostname, transport protocol (smtp/lmtp),
+transport ports and mail domains (or just single email addresses)
+of your additional e-mail servers. When transport protocol is set to `lmtp`,
+the option 'Use MX' is useless and will be automatically set to 'No'.
 
 
 [[pmgconfig_mailproxy_networks]]