User blog comment:FastLizard4/Mailing List, Anyone?/@comment-5163008-20120719003205/@comment-140200-20120719045551

I guess I should have explained this better on the subscription form. Digested means that you'll receive all the messages sent to the list batched all together in a daily email; that is, you'll receive no more than one email per day, containing all the discussion that happened on the list on that day. Non-digested means that you'll receive emails in real time, immediately as they are received the server.