Allow devices without auth token into my server

Hello i have some ESP8266 chips that act as water alarms and all they do is end a email through the server, I would like to make them so there is no auth token is there a way to do that?

They could all have the same token if you allocate one of the 128 virtual pins to each device and get a master device to send the emails based on the content of the virtual pin.

If the ESP’s are all physically connected you wouldn’t need any token but I guess the ESP’s will be in different locations.