diff --git a/doc/dev/dolibarr-doxygen.conf b/doc/dev/dolibarr-doxygen.conf
index a880fc0a854..d3b4110ac19 100644
--- a/doc/dev/dolibarr-doxygen.conf
+++ b/doc/dev/dolibarr-doxygen.conf
@@ -572,6 +572,7 @@ EXCLUDE                = mssql \
                          htdocs/includes/phplot5 \
                          htdocs/includes/pwc \
                          htdocs/includes/scriptaculous \
+                         htdocs/includes/simplemail \
                          htdocs/includes/smtps \
                          htdocs/includes/vcard \
                          htdocs/avoir \