Tweak docs on difference between "local" and "remote" source messages

diff --git a/doc/doc-docbook/spec.xfpt b/doc/doc-docbook/spec.xfpt
index 8552400cf9d75bba73eba66974548044050f0882..534e1b8f346bb90ec3249188c4115ed81e3f7b4b 100644 (file)
--- a/doc/doc-docbook/spec.xfpt
+++ b/doc/doc-docbook/spec.xfpt
@@ -12152,8 +12152,9 @@ the &%-bs%& or &%-bS%& options.
 
 .vitem &$sender_host_address$&
 .vindex "&$sender_host_address$&"
-When a message is received from a remote host, this variable contains that
-host's IP address. For locally submitted messages, it is empty.
+When a message is received from a remote host using SMTP,
+this variable contains that
+host's IP address. For locally non-SMTP submitted messages, it is empty.
 
 .vitem &$sender_host_authenticated$&
 .vindex "&$sender_host_authenticated$&"