SMTP service droplet for IOT messages

One of my clients manufactures emergency lighting systems for commercial buildings. About 8 years ago I designed firmware for them that includes the capability to email automated test results and problem alerts to customers who’ve installed one or more of their products.

The product has been a success and they have hundreds of these systems installed at customer sites.

Presently, these systems, by default, use a dedicated gmail account to send messages via Google’s SMTP servers. The traffic is light, a few messages per month for each system. This approach has worked very well until recently.

Google has been notifying account holders that as of May 30, 2022 this approach will no longer be supported.

The firmware on my client’s system has the capability change the port, SMTP host address, sender address and password. Anything more elaborate would require an expensive reinstallation of upgraded firmware.

I’m looking into the feasibility of setting up a dedicated SMTP relay in a Droplet. Some guidance on the best way to do this would be really helpful.

Thanks!