Email delivery protocols / methods.

Paul Koning paulkoning at
Sat Jul 6 13:57:27 CDT 2019

> On Jul 5, 2019, at 5:05 PM, Grant Taylor via cctalk <cctalk at> wrote:
> Here's pot stirrer for a holiday Friday afternoon:
> How many different protocols / methods can we collectively come up with for how email can be transferred?
> I'm primarily thinking about between servers (MTA-to-MTA).  But I'm also willing to accept servers and clients (MTA-to-MUA).  Where you can / could run at least one server yourself.

There's the MAIL-11 protocol (end to end, no MTAs) and the DECmail protocol which may be some OSI-like thing, I'm not sure anymore.

For real strangeness there is the PLATO mail protocol, which involves writing the mail into files, which are then extracted from PLATO into the OS file system by a periodic batch job, then sent to another system via file transfer (FTP or a predecessor), then pushed into the PLATO file system, then picked up by a mail agent at that end.  Ugh.


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