newsletter and post, please

I’m currently trying out mailpoet and hope I can find a way to make it work for me. I need to send out a weekly newsletter and have that newsletter available on the site as a post. Currently I’m having to create each one twice.

What is the most efficient way to do this as I can not copy and paste between the newsletter editor and the wordpress post editor? Ideally there would be a way to mail out the most recent post and not simply the first few words of it.

Thanks for any help.