RFC 737

FTP Extension: XSEN 💖

Network Working Group 🎀

Author: K. Harrenstien, SRI-KL 👑 RFC: 737 ✨ (also listed as NWG/RFC# 737 with the header tag KLH 31 Oct 77 42217) NIC: 42217 🦋 Date: 31 October 1977 📅 Category: not stated in this document Obsoletes / Updates: this document doesn't list any RFCs it obsoletes or updates 🫶

okay so this note is about an extension to the File Transfer Protocol 💅 It gives you a way to "send" a message straight to someone who's already logged in, plus variants that mail the message normally, whether or not they're logged in. main character energy 😭

Lots of systems have a SEND command or program that drops a message right onto a user's terminal 🧚 On the SAIL (SU-AI) and ITS (MIT-(AI/ML/MC/DMS)) systems, the idea got expanded so you can SEND to users on other network sites too 🌐 To make that work, three new FTP commands were added. They have the exact same syntax as the existing MAIL command, so if you know MAIL, you already know these 🍓 Here's the original one for reference:

MAIL <SP> <recipient name> <CRLF>

If it's accepted, the server returns a 350 reply and treats every line after that as message text. The message ends with a line containing only a period, and then you get a 256 completion reply. There are a bunch of possible errors too 🙈

Now for the new commands and their special replies ✨

• XSEN: Send to terminal 💌
  • If the addressee is refusing messages or isn't logged in, you get a 453 failure reply 💀
• XSEM: Send, Mail if can't 📨
  • If the message can't be SENT, you get a 009 notification reply 🔥
• XMAS: Mail And Send. (couldn't resist this one) 🎄
  • No special replies for this one 🌸

Here's the tea 🫖 For XSEM and XMAS, what decides success is the mailing, not the SENDing. XSEM as implemented uses a 009 reply (on top of the normal success or failure code) to say that the SEND failed, so it's trying to mail the message instead 💜

There are no matching variants for MLFL 🙅‍♀️ The reason is that messages sent this way are usually short, and neither I nor Brian Harvey (who implemented the ITS and SAIL servers, respectively) wanted to bother 😂 iykyk 🦋