Test Mail Works but Campaign mail is not sent

Product Support
1

I have queued 10000+ emails for sending in batches of 50.

I see the messages in ‘spool’ directory, but somehow, messages are not being sent. There is no error at apache error log.

I get this error from Mautic log file :

2016-04-05 12:30:34] mautic.ERROR: Swift_TransportException: Expected response code 250 but got code “421”, with message "421 4.7.0 <my-email-host.com Error:$Error: too many errors " (uncaught exception) at /var/www/html/mautic/vendor/swiftmailer/swiftmailer/lib/classes/Swift/Transport/AbstractSmtpTransport.php line 383

2

I have queued 10000+ emails for sending in batches of 50.
I see the messages in ‘spool’ directory, but somehow, messages are not being sent. There is no error at apache error log.
I get this error from Mautic log file :
2016-04-05 12:30:34] mautic.ERROR: Swift_TransportException: Expected response code 250 but got code “421”, with message "421 4.7.0 <my-email-host.com Error:$Error: too many errors " (uncaught exception) at /var/www/html/mautic/vendor/swiftmailer/swiftmailer/lib/classes/Swift/Transport/AbstractSmtpTransport.php line 383

3