Don't automate these emails. People can tell and they won't respond. Even the WIP email you mentioned gets a very low response rate despite it being short and personal.
It seems like you only got a couple dozen email subscribers, so you should be able to manually email them. Research them for a bit (google their email address, but don't go over board into creepy territory) and make the email personal. About them.
It's a lot more work and not scalable to do forever for a large amount of subscribers. But for those first 100 subscribers or so, you should totally be able to do it. And you'll get a much better response rate.
Don't automate these emails. People can tell and they won't respond. Even the WIP email you mentioned gets a very low response rate despite it being short and personal.
It seems like you only got a couple dozen email subscribers, so you should be able to manually email them. Research them for a bit (google their email address, but don't go over board into creepy territory) and make the email personal. About them.
It's a lot more work and not scalable to do forever for a large amount of subscribers. But for those first 100 subscribers or so, you should totally be able to do it. And you'll get a much better response rate.