diff --git a/Usage-Documentation.md b/Usage-Documentation.md
index a8f715f..a6009fa 100644
--- a/Usage-Documentation.md
+++ b/Usage-Documentation.md
@@ -102,6 +102,12 @@ Need HTML output? Just pipe through "aha" (Ansi HTML Adapter: github.com/theZiz/
 
    `testssl.sh <options> <URI> | aha >output.html`
 
+
+### STARTTLS
+
+For STARTTLS you need to aim at the text/plain port, provide ``-t/--smtp`` and the port : ``testssl.sh -t smtp smtp.gmail.com:25`` or e.g. ``testssl.sh -t imap imap.gmx.net:143``. Please note that for plain encrypted ports you do not have to specify the protocol option: ``testssl.sh smtp.gmail.com:465`` tests the encryption on the SMTPS port, ``testssl.sh imap.gmx.net:993`` on the IMAPS port.
+
+
 ### Exit status
 
 **0**    testssl.sh finished sucessfully