Merge branch 'jk/asciidoctor-section-heading-markup-fix'

diff --git a/git-send-email.perl b/git-send-email.perl
index c5a3f766f7fd34a48b352f3cfbb901840b4c4d5b..e3ff44b4d0cd25f247138d9ead160d2aedff5033 100755 (executable)
--- a/git-send-email.perl
+++ b/git-send-email.perl
@@ -1136,7 +1136,7 @@ sub smtp_auth_maybe {
 
        # Check mechanism naming as defined in:
        # https://tools.ietf.org/html/rfc4422#page-8
-       if ($smtp_auth !~ /^(\b[A-Z0-9-_]{1,20}\s*)*$/) {
+       if ($smtp_auth && $smtp_auth !~ /^(\b[A-Z0-9-_]{1,20}\s*)*$/) {
                die "invalid smtp auth: '${smtp_auth}'";
        }