Automatic New Blogpost Widget – remove posts or reset what is new?

MailPoet v3

I’ve deinstalled v2, installed v3, imported all subscribers and created my old newsletter from scratch with v3. So far so good.

But now the widget for “automatic new blog posts” is inserting all “old” posts too that were sent with v2 already (sure, v3 doesn’t know that ;))

So is there a way to either remove posts out of this list manually – or reset the indicator for v3 to decide what is “new”?

Thanks a lot