A person may be having trouble receiving mail from a specific email address, domain, or network on their GreyMail account. The sender may be receiving a 570 error code.
GreyMail protects users inboxes by using industry standard practices, in this case, we utilize reverse DNS checks on the email server to ensure it's legitimate. This ensures that the responsible party is not infected and is a legitimate email server/service.
This error is caused by poor email server setup on the senders end and can easily be resolved by the sender.
The below example error may not look exactly like the below:
570 Your server IP does not have a valid reverse DNS entry
Please have the sender contact their IT department or whoever manages their email server. This is not an issue on GreyMail's end.