All codes are below:
Swift_TransportException: Email to ....@gmail.com failed: Expected response code 354 but got code "503", with message "503 5.5.4 Bad sequence of commands. " src/vendor/swiftmailer/swiftmailer/lib/classes/Swift/Transport/AbstractSmtpTransport.php:457
i am having errors while sending bulk message or email to all members. i am using SMTP. there is no problem for single message or mail or email notifications.
its only with bulks.
why this error and what to do solve it?