More than likely it will require some sort of secure access, but I was hoping there would be a library pre-made for some sender, similar to what people have done for Telegram. Sendgrid has some stuff, but I'm not interested in using nodeJS or other cruft. My goal is to have a device that is completely standalone and sits outside my network - either on someone else's and/or on my fallback cellular network - and checks to see if my network resolves, and tell me when it doesn't. I want as simple a device as possible, so having something like a postfix server running as a relay isn't my goal. It has to be able to recover from a hard power cut without intervention.