The response from Amazon is quite cute! Emails aren't arriving... so it must be email problems!
If Amazon are using their own SES (Amazon Simple Email Service) then this does use a suppression list. What happens is that there's a temporary difficulty in getting email to your mailbox and if, after a retry, there's still no delivery then SES adds your email address to their suppression list. This will stop any more mail being sent out. It's a standard technique. Some customer service agents may not have access to the sender suppression list so may need to ask their email admins to whitelist your address or just remove it from the suppression list.
