Send hundreds of outgoing mails within seconds

Hunted this via the creator @KevGroenendaal, a side-project that seems to deserve a lot more attention than it's got now. It's very minimal and lets you mass-mail hundreds of recipients from OSX. All messages are sent individually.
Looks interesting and definitely solves a problem. To play the devils advocate - have you thought about how this could conflict with the SPAM rules?
@jamesepember If the addresses you're reaching out to have already opted-in to receive email correspondence from you, you're all good. Looks like this solution would be good when you don't have a large enough sample size for typical A/B and drip campaigns, and you just need to get a generic email out to an audience.
I'd like to know when it got worrying to be flagged as a spammer here. It'd be helpful to see some use cases shown on the website.