Why It Was Gone for So Long
GSM actually has a longer history than most people expect.
I originally wrote GSM around 2017 and made it public in 2018. To my surprise, it took off pretty quickly. The user base grew to more than 40,000 users, and even more surprising: it ran with relatively few bugs. Things looked solid.
Then Google changed the rules.
Google introduced a new and much stricter validation process for apps accessing Gmail, Drive, and other services. Suddenly, GSM required a complex security assessment. I tried to reduce the number of Google services used as much as possible and spent roughly 200 hours rewriting large parts of the code.
When I finally looked into starting the validation, I got a real shock: the estimated costs were between 15,000 and 25,000 USD per year, plus ongoing development effort. That was completely out of reach and simply didn’t fit the idea of a free Mail Merge tool.
Honestly, that was a tough moment. GSM was limited by Google to 100 users, and watching thousands of users slowly drop off was frustrating and disappointing. It took some time to recover from that.
Over the following years, I worked on GSM on and off. Eventually, I decided to give it another try with GSM 2.0 and see how the validation process looks today. It’s still not easy, but it’s much better than before. I spent another ~100 hours coding and around 50 hours just going through the validation steps.
The cost now is around 2,000 USD per year with the current feature set. Not cheap, but way cheaper the initally.
GSM lost some features, gained others, supports 22 interface languages, and runs with the lowest possible permissions. It is completely isolated: no external calls, no data leaving the system. Nothing goes in, nothing goes out. That’s also why a separate data privacy agreement isn’t really needed.
If you’re curious which feature uses which permission, check out the YouTube video. It’s part of the official Google validation process.
If you don’t like apps that ask for excessive permissions, GSM might be for you. 🙂
Happy Mailing with GSM, Klaus