How to Warm Up a Very, Very Cold Email List From Previous Product?

I am currently working on the marketing for my current product, Product B.

For my previous product, Product A, I failed to get any paid customers. But I did collect a lot of free users’ emails, around 300 people in total. The painful part is that I never really took care of that email list.

Now I am wondering: for Product B, does it make sense to slightly reintroduce myself to that previous email list and gently introduce what I am building now? What is a doable strategy? I cut the list into very small batches and tested different subject lines, but honestly, none of them worked.

Has anyone tried this before?