A Paymail server is a very lean and modular service. It is not an integral part of wallet infrastructure, but instead can be thought of as an extension layer on top that functions to enhance the user experience. It can be peeled on/off but if it is not available, then things should still be able to function at a lower level without it. In fact, in cases where service discovery has already been reached, through a QR code or an NFC connection for instance, Paymail is not exactly needed since the communication process is already past service discovery. In other words, if a sender wants to send a reciever a payment and the sender already has direct access to the reciever somehow, by scanning a QR code on their phone for example, then the QR code scanning process already served as the service discovery phase. The process can proceed directly to the communication of the payment from the sender to the receiver.