Receiving a payment confirmation through "mailer@shopify.com"

I have an eTransfer payment method that allows users to send eTransfers after an order is placed. I usually receive the eTransfer, then mannually confirm the payment in the customer’s order profile. For some odd reason, I just received an email from mailer@shopify.com stating the following:

but I haven’t received any payment yet in my business account. Could someone please explain to me why I am receiving this email?