Help an oldfag get up to date on email. Back in the day you would just read RFC822 to know how email works. What are the technologies now? What RFCs should I know about?
What are the email servers and their qualities? I remember:
* Sendmail was always getting hacked and no one could maintain it with a book
* postfix was getting popular
* I think djb rolled his own
* hell, I rolled my own forwarder once
What are the connection protocols?
* There was POP that let customers accidentally delete their inboxes whenever they read their email from a friend's computer, IMAP, MAPI that no one else supported, and everyone skips those and uses web based email now.
* Microsoft had some protocol to push emails to its handhelds that was always hanging and you needed to schedule a script to delete ds2mb every hour to work around it.
* Is there anything new in server-to-server protocols or are they still sending flat RFC821/RFC822 to each other?
What are the recommended storage formats? Those I know of are:
1. mbox - One flat text file per mail folder.
2. maildir - A nest of subdirectories with one file per message that takes forever to load off a HDD.
How does one encrypt mail like Protonmail or Tutanota?
1. encrypt storage so the host can't read it?
2. encrypt comms to other SMTP servers if they support it?
What about spam fighting? There were a bunch of groups in the late 1990s that went silent and underground in the early 2000s, especially after Usenet died.
Speaking of Usenet, how does one get back on it without going through Google Groups or "pay for binz" sites? Every ISP that I know of has shut down their usenet servers. Is anyone still on it or is it all spam and tumbleweeds?
How does one create a cluster with multiple physical servers serving one email domain? Is this done at a lower level?
What webmail frontends are recommended? Squirrelmail was once the standard but it has been abandoned for years.
Is there anything new that needs to go into DNS to make email work better? Any special TXT tags?
What else should a techie know about email today?