by Darius Kazemi, August 9 2019

In 2019 I'm reading one RFC a day in chronological order starting from the very first one. More on this project here. There is a table of contents for all my RFC posts.

FTP for mail

RFC-221 is titled “A Mail Box Protocol, Version-2”. It's by Richard Watson of SRI-ARC and dated August 25, 1971.

The technical content

This RFC updates RFC-196, which is a proposal for a protocol for an email-like thing. The original proposal uses the Data Transfer Protocol for data transfer, but Network Working Group members would prefer to use File Transfer Protocol so this RFC incorporates that protocol instead.

The big issue with using FTP for the Mail Box Protocol is that FTP assumes the user understands something about the file system and path names of the remote site. The Mail Box Protocol would ideally not involve the end user who is sending a message to know anything about the file system of the recipient.

The proposed solution is for the ARPANET sites to agree on a virtual pathname for a Mail Box, then connect via FTP to the special Mail Box socket, issue an Append request to the path, and pass the ASCII string “NETMAIL” followed by an 8-bit byte corresponding to a mail box number. This would mean each host computer could support up to 256 inboxes.

The issue of spam and abuse is raised (”the possibility of someone accidentally or deliberately flooding the printer of a site with garbage”), but no good solutions have been discovered. The suggestion is made that the protocol not involve any safeguards and that it's up to individual sites to add their own safeguards, though perhaps at a later date there could be standards for safety agreed upon by all.


I'm wondering why they would have to agree on a path name at all for the Mail Box, when there is already a specific socket reserved for the protocol. Individual host sites could simply interpret any Append request from FTP on the mail box socket as a request to append to the local mail box, wherever it happens to be on the file system.

A purely nerdy aside is that the end note of the RFC lists the author as “Richard W. Watson/RWW”, which means he typed up this RFC himself. I've wondered what percentage of RFC documents are prepared by secretarial workers...

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About me

I'm Darius Kazemi. I'm an independent technologist and artist. I do a lot of work on the decentralized web with ActivityPub, including a Node.js reference implementation, an RSS-to-ActivityPub converter, and a fork of Mastodon, called Hometown. You can support my work via my Patreon.