IFTTT uses "recipes" to chain together two services (if something happens here, do this). For example, given a RSS feed of recent messages to EvolDir, I can create a recipe to send the links to those posts to Twitter:
Great, only EvolDir is an old-fashioned mailing list distributed by email only. There is no web site for the list that has URLs to each post, and no RSS feed. IFTTT to the rescue again. I created a recipe that reads emails for a GMail account that is subscribed to EvolDir, and each time it gets an email from EvolDir it sends the contents of the email to a blog on Tumblr:
Now each post has a web presence, and Tumblr generates a RSS feed for the blog, so the first recipe can take that feed and every time the feed is updated it will send that post to Twitter. Simples.