payment duplicate & support email not working

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The user you are trying to contact is receiving mail at a rate that prevents additional messages from being delivered. Please resend your message at a later time. If the user is able to receive mail at that time, your message will be delivered. For more information, go to https://support.google.com/mail/?p=ReceivingRate

Final-Recipient: rfc822; support@grindinggear.com
Action: delayed
Status: 4.2.1
Diagnostic-Code: smtp; The user you are trying to contact is receiving mail at a rate that prevents additional messages from being delivered. Please resend your message at a later time. If the user is able to receive mail at that time, your message will be delivered. For more information, go to https://support.google.com/mail/?p=ReceivingRate
Last-Attempt-Date: