When using STARTTLS the SSL_verifycn_name must be set to prevent SSL

Errors

VIRTUAL_VACATION/vacation.pl

@@ -168,7 +168,12 @@ our $smtp_client = 'localhost';
 
 # send mail encrypted or plaintext
 # if 'starttls', use STARTTLS; if 'ssl' (or 1), connect securely; otherwise, no security
-our $smtp_ssl = '';
+our $smtp_ssl = 'starttls';
+
+# passed to Net::SMTP constructor for 'ssl' connections or to starttls for 'starttls' connections; should contain extra options for IO::Socket::SSL
+our $ssl_options = {
+	SSL_verifycn_name => $smtp_server
+};
 
 # maximum time in secs to wait for server; default is 120
 our $smtp_timeout = '120';
@@ -556,6 +561,7 @@ sub send_vacation_email {
 		my $smtp_params = {
 			host => $smtp_server,
             port => $smtp_server_port,
+            ssl_options => $ssl_options,
 			ssl  => $smtp_ssl,
 			timeout => $smtp_timeout,
 			localaddr => $smtp_client,