Yes. Simply use the RSS feed to trigger the e-mail with the RSS Campaign in Mailchimp. You’ll need to make sure that your Jekyll site is creating an RSS feed.
We recently started working on www.postbear.io which will allow you to send automated newsletters from Jekyll posts. It would be great to get some feedback from you.
And yes, the RSS feed could be used by a RSS to email service
Like Mailchimp for example or mailerlite. The link to postbear is not working anymore but there is also https://www.rssfeedpulse.com (simpler solution than mailchimp)