Kayako Support Desk Errors

Uncaught Exception
Expected response code 220 but got code "421", with message "421 4.4.5 Server busy, try again later. (mx.google.com) g4sm55605691obe.5 - gsmtp
" in ./__swift/thirdparty/SwiftMailer/classes/SwiftMailer/Transport/AbstractSmtpTransport.php:422
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#0 ./__swift/thirdparty/SwiftMailer/classes/SwiftMailer/Transport/AbstractSmtpTransport.php(315): SwiftMailer_Transport_AbstractSmtpTransport->_assertResponseCode('421 4.4.5 Serve...', Array)
#1 ./__swift/thirdparty/SwiftMailer/classes/SwiftMailer/Transport/AbstractSmtpTransport.php(123): SwiftMailer_Transport_AbstractSmtpTransport->_readGreeting()
#2 ./__swift/thirdparty/SwiftMailer/classes/SwiftMailer/Mailer.php(79): SwiftMailer_Transport_AbstractSmtpTransport->start()
#3 ./__swift/library/Mail/class.SWIFT_Mail.php(529): SwiftMailer_Mailer->send(Object(SwiftMailer_Message))
#4 ./__apps/tickets/library/Ticket/class.SWIFT_TicketEmailDispatch.php(1154): SWIFT_Mail->SendMail(false, 1)
#5 ./__apps/tickets/library/Ticket/class.SWIFT_TicketEmailDispatch.php(290): SWIFT_TicketEmailDispatch->Dispatch(2, '<font face="Ver...', 'No problem Jayn...', 'Krystal Milne', 'support@hbsaonl...', 'jayneeholt@yaho...', '', Array, Array, '', '')
#6 ./__apps/tickets/models/Ticket/class.SWIFT_TicketPost.php(306): SWIFT_TicketEmailDispatch->DispatchStaffReply(Object(SWIFT_Staff), 'No problem Jayn...', false, 'support@hbsaonl...', Array)
#7 ./__apps/tickets/staff/class.Controller_Ticket.php(3501): SWIFT_TicketPost::CreateStaff(Object(SWIFT_Ticket), Object(SWIFT_Staff), 2, 'No problem Jayn...', '', false, false, 'support@hbsaonl...', false)
#8 [internal function]: Controller_Ticket->ReplySubmit('102567', 'mytickets', '-1', '-1', '-1', '0')
#9 ./__swift/library/MVC/class.SWIFT_Controller.php(369): call_user_func_array(Array, Array)
#10 ./__swift/library/App/class.SWIFT_App.php(176): SWIFT_Controller::Load(Object(SWIFT_Interface), Object(SWIFT_App), Object(SWIFT_Router), false)
#11 ./__swift/library/class.SWIFT.php(16): SWIFT_App->ExecuteController(Object(SWIFT_Router))
#12 ./__swift/library/class.SWIFT.php(16): SWIFT->Initialize()
#13 ./__swift/swift.php(16): SWIFT::GetInstance()
#14 ./staff/index.php(29): require_once('/home/thesuppo/...')
#15 {main}