There's no such method as has_option() -- should be has_extn().
diff --git a/Doc/lib/libsmtplib.tex b/Doc/lib/libsmtplib.tex
index c41057d..2f6e59e 100644
--- a/Doc/lib/libsmtplib.tex
+++ b/Doc/lib/libsmtplib.tex
@@ -138,9 +138,9 @@
Identify yourself to an ESMTP server using \samp{EHLO}. The hostname
argument defaults to the fully qualified domain name of the local
host. Examine the response for ESMTP option and store them for use by
-\method{has_option()}.
+\method{has_extn()}.
-Unless you wish to use \method{has_option()} before sending
+Unless you wish to use \method{has_extn()} before sending
mail, it should not be necessary to call this method explicitly. It
will be implicitly called by \method{sendmail()} when necessary.
\end{methoddesc}