Urantia has several different newsletters that used to be exclusively in print format. I instructed them to move their newsletter articles to their blog where web visitors could read them, and then group articles from same newsletter together in an email that could be sent out. To brand their newsletters differently, their template includes a default header that they can override by uploading a new image. They also use their newsletter for support appeals, in which case they simply type the content they want into the WordPress editor.
They have several different email lists in MailChimp, so before they send a newsletter, they select which list to send it to. Then when they’re ready, it is automatically sent out via MailChimp.