RFC 706

On the Junk Mail Problem 💌

okay bestie, let's get into RFC 706 🎀 The title block says it's by Jon Postel (SRI-ARC) 🧚, from the Network Working Group, dated Nov 1975, with NIC #33861 as its number. The original doesn't list anything it obsoletes or updates, so I'm not claiming any 🌸

The core problem is kind of a mess 😭 In the ARPA Network Host/IMP interface protocol, there's no way for a Host to selectively refuse messages. So a Host that wants only certain messages still has to read every single message addressed to it. A malfunctioning Host could flood it with tons of messages, and that's basically a denial of service for the normal users of that Host 💀 Both the local users and the network communication can suffer. The stuff that gets wasted is the processor time spent examining and rejecting the unwanted messages, plus the loss of network thruput or the extra delay from all that unnecessary busyness on the network.

It would be so useful if a Host could decline messages from sources it thinks are misbehaving, or just annoying 🙈 If the Host/IMP interface protocol let the Host tell the IMP "refuse messages from Host X", the IMPs could toss the unwanted messages at their earliest opportunity and send back a "refused" notice to the offending Host. Main character energy, honestly ✨

How the IMPs actually pull this off is still an open issue 🦋 Here are two possibilities:

1. The destination IMP keeps a list (per local Host) of sources to refuse. Heads up, this has the disadvantage of keeping the network busy 😬
2. The destination IMP, on receiving the "refuse messages from Host X" message, forwards that message to the source IMP (the IMP local to Host X). That IMP then keeps a list (per local Host) of destinations that are refusing messages from this source Host 👑

The restriction on messages can be lifted by the destination Host, either by sending an "accept messages from Host X" message to the IMP, or by resetting its Host/IMP interface 🫶

A Host could use this whole feature by measuring, per source, the number of undesired messages per unit time. If that measure goes over a threshold, then the Host could issue the "refuse messages from Host X" message to the IMP. Honestly iconic, periodt 💅🌈