vBulletin 3.8.11 SMTP Issues

[Tobias Pohlmann]

[COLOR=#839496][FONT=Consolas][SIZE=14px]The mailing function returned an error while trying to send the mail.
The following errors were outputted by PHP when attempting to send mail:

PHP Warning: fsockopen(): Peer certificate CN=`ubuntu' did not match expected CN=`webmail.xxxxxxx.net' in ..../includes/class_mail.php on line 654

PHP Warning: fsockopen(): Failed to enable crypto in ..../includes/class_mail.php on line 654

PHP Warning: fsockopen(): unable to connect to ssl://webmail.xxxxxx.net:465 (Unknown error) in ..../includes/class_mail.php on line 654

PHP User Warning: Unable to connect to SMTP server in ..../includes/class_mail.php on line 612[/SIZE][/FONT][/COLOR]

Getting some error only in vBulletin 3.8.11 on 4.2.5 this error is not there. What is wrong with that? I can login normaly in ma E-Mail server Software but vBulletin shows error!