Sounds like a missed opportunity for a bot then... It is not like you are really personalizing the message at all. The only human part of this would be deciding which photo to use to entice the developer. (Could this be optimized by a bot and A/B testing?)
I agree with the other comments that this is a useful feature, but would be more well suited for a customized twitter account with a name explaining it better.
the idea of a bot is intriguing, but right now I'm manually finding founders contact info, reaching out, getting them in the system, asking them Q+A's on producthunt.com, cc'ing other relevant players in the convo, and following up with them to see how PH influenced their traffic and how we can help (which, again, founders respond gratefully for all the free traffic)
If anyone has suggestions for ways to automate part of this, as it takes a long time, i'm open!
Ever try emailing founders instead? I wonder if you'd get a better and/or faster response.
Perhaps you could require your product submitters to insert the contact email for the products they are submitting. Then, you could auto email the founder as soon as their product is posted on Product Hunt.
Many of them respond with a "Thanks". Not one person has said "Spam".