Excerpt from this article:
We now find ourselves in the era of the personal email newsletter, an almost retro delivery system that blurs borders between the public and the private, and mashes up characteristics of the analog and digital ages.
Thanks to, among other services, TinyLetter, a division of the email marketer MailChimp, people who want to apprise a subscriber base of their thoughts and goings-on have a new, straight-to-inbox outlet.
…There is an old-fashioned aspect to the TinyLetter. Entries can be archived for public consumption, effectively turning it into a blog. But some writers, such as Ms. Shane, do not save them for posterity, so the only way to read certain newsletters is to subscribe and receive them at the moment they are sent.
Thus they hark back to the ephemerality of pre-internet media consumption, when one likely had to buy a periodical to read that specific issue or watch a TV show in its broadcast time slot or else risk missing it forever.