Xenforo Mailgun Error

I tried Amazon SES, Mailgun, Mandrill, SendGrid. There will be an error, unable to send mail. I shut down the firewall. I use the curl and smtp method to test the send mail is successful. Only xenforo cannot send mail.

Code:

phpinfo()                                                                                                                                                                                   
PHP Version => 7.0.14                                                                                                                                                                       

System => Linux iZ28mlek4q6Z 3.10.0-514.2.2.el7.x86_64 #1 SMP Tue Dec 6 23:06:41 UTC 2016 x86_64                                                                                             
Build Date => Dec 14 2016 13:22:06                                                                                                                                                           
Configure Command =>  '../configure'  '--enable-fpm' '--enable-opcache' '--enable-intl' '--enable-pcntl' '--with-mcrypt' '--with-snmp' '--with-mhash' '--with-zlib' '--with-gettext' '--enable-
exif' '--enable-zip' '--with-bz2' '--enable-soap' '--enable-sockets' '--enable-sysvmsg' '--enable-sysvsem' '--enable-sysvshm' '--enable-shmop' '--with-pear' '--enable-mbstring' '--with-openss
l' '--with-mysql=mysqlnd' '--with-libdir=lib64' '--with-mysqli=mysqlnd' '--with-mysql-sock=/var/lib/mysql/mysql.sock' '--with-curl' '--with-gd' '--with-xmlrpc' '--enable-bcmath' '--enable-cal
endar' '--enable-ftp' '--enable-gd-native-ttf' '--with-freetype-dir=/usr' '--with-jpeg-dir=/usr' '--with-png-dir=/usr' '--with-xpm-dir=/usr' '--with-vpx-dir=/usr' '--with-t1lib=/usr' '--enabl
e-pdo' '--with-pdo-sqlite' '--with-pdo-mysql=mysqlnd' '--enable-inline-optimization' '--with-imap' '--with-imap-ssl' '--with-kerberos' '--with-readline' '--with-libedit' '--with-gmp' '--with-
pspell' '--with-tidy' '--with-enchant' '--with-fpm-user=nginx' '--with-fpm-group=nginx' '--disable-fileinfo' '--with-ldap' '--with-ldap-sasl' '--with-config-file-scan-dir=/etc/centminmod/php.
d' '--with-xsl'                                                                                                                                                                             
Server API => Command Line Interface                                                                                                                                                         
Virtual Directory Support => disabled                                                                                                                                                       
Configuration File (php.ini) Path => /usr/local/lib                                                                                                                                         
Loaded Configuration File => /usr/local/lib/php.ini                                                                                                                                         
Scan this dir for additional .ini files => /etc/centminmod/php.d                                                                                                                             
Additional .ini files parsed => /etc/centminmod/php.d/a_customphp.ini,                                                                                                                       
/etc/centminmod/php.d/curlcainfo.ini,                                                                                                                                                       
/etc/centminmod/php.d/geoip.ini,                                                                                                                                                             
/etc/centminmod/php.d/igbinary.ini,                                                                                                                                                         
/etc/centminmod/php.d/imagick.ini,                                                                                                                                                           
/etc/centminmod/php.d/ioncube.ini,                                                                                                                                                           
/etc/centminmod/php.d/mailparse.ini,                                                                                                                                                         
/etc/centminmod/php.d/redis.ini,                                                                                                                                                             
/etc/centminmod/php.d/zendopcache.ini,                                                                                                                                                       
/etc/centminmod/php.d/zzzz_phpsessions.ini   

Code:

Server Error

Unable to Connect to ssl://api.mailgun.net:443. Error #0:

Zend_Http_Client_Adapter_Socket->connect() in Zend/Http/Client.php at line 973
Zend_Http_Client->request() in bdMails/Transport/Mailgun.php at line 118
bdMails_Transport_Mailgun->bdMails_getWebhooks() in bdMails/XenForo/ControllerAdmin/Tools.php at line 9
bdMails_XenForo_ControllerAdmin_Tools->actionMailgunWebhooksAdd() in XenForo/FrontController.php at line 351
XenForo_FrontController->dispatch() in XenForo/FrontController.php at line 134
XenForo_FrontController->run() in /home/domains.com/public/admin.php at line 13

Code:

Zend_Http_Client_Adapter_Exception: Email to xxx@xxx.com failed: Unable to Connect to ssl://api.mailgun.net:443. Error #0: - library/Zend/Http/Client/Adapter/Socket.php:235
Stack
#0 /home/xxx/public/library/Zend/Http/Client.php(973): Zend_Http_Client_Adapter_Socket->connect('ssl://api.mailg...', 443, true)
#1 /home/xxx/public/library/bdMails/Transport/Mailgun.php(96): Zend_Http_Client->request('POST')
#2 /home/xxx/public/library/bdMails/Transport/Abstract.php(31): bdMails_Transport_Mailgun->_bdMails_sendMail()
#3 /home/xxx/public/library/Zend/Mail/Transport/Abstract.php(348): bdMails_Transport_Abstract->_sendMail()
#4 /home/xxx/public/library/Zend/Mail.php(1194): Zend_Mail_Transport_Abstract->send(Object(Zend_Mail))
#5 /home/xxx/public/library/XenForo/Deferred/UserEmail.php(168): Zend_Mail->send(Object(bdMails_Transport_Mailgun))
#6 /home/xxx/public/library/XenForo/Deferred/UserEmail.php(62): XenForo_Deferred_UserEmail->_sendEmail(Array, Array, Object(bdMails_Transport_Mailgun))
#7 /home/xxx/public/library/XenForo/ControllerAdmin/User.php(1197): XenForo_Deferred_UserEmail->execute(Array, Array, 10, NULL)
#8 /home/xxx/public/library/XenForo/FrontController.php(351): XenForo_ControllerAdmin_User->actionEmailSend()
#9 /home/xxx/public/library/XenForo/FrontController.php(134): XenForo_FrontController->dispatch(Object(XenForo_RouteMatch))
#10 /home/xxx/public/admin.php(13): XenForo_FrontController->run()
#11 {main}

array(3) {
  ["url"] => string(41) "https://xxxxx/admin.php?users/email-send"
  ["_GET"] => array(1) {
    ["users/email-send"] => string(0) ""
  }
  ["_POST"] => array(10) {
    ["test"] => string(18) "test mail"
    ["criteria"] => string(117) "{"receive_admin_email":"1","email":"demo@123.com","user_state":["valid"],"is_banned":["0"],"no_empty_email":true}"
    ["total"] => string(1) "1"
    ["from_name"] => string(13) "demos"
    ["from_email"] => string(18) "no-reply@*****"
    ["email_title"] => string(11) "23423423423"
    ["email_format"] => string(4) "text"
    ["email_body"] => string(14) "42342342342343"
    ["_xfConfirm"] => string(1) "1"
    ["_xfToken"] => string(8) "********"
  }
}

---