1 files changed, 3 insertions, 2 deletions

diff --git a/doc/smtp.html b/doc/smtp.html
index 2ef673a..bbbff80 100644
--- a/doc/smtp.html
+++ b/doc/smtp.html
@@ -90,8 +90,9 @@ headers = {<br>
 </blockquote>
 
 <p>
-Field names are case insensitive (as  specified by the standard) and all
-functions  work with  lowercase field names.  
+Field names are case insensitive (as specified by the standard) and all
+functions work with lowercase field names (but see
+<a href=socket.html#headers.canonic><tt>socket.headers.canonic</tt></a>).
 Field values are left unmodified.
 </p>