[Douglas asked me to forward this to the list]
I disagree. The only resource that will be hit is the message haven (unlike say every computer in the world that carries the certain usenet group you have chosen to use as a communications vehicle). Geez, think of like a place that offers anonymous ftp. It's resources are hit, but I don't buy the "massive load on net.resources". You think so? Hm. I'm just pulling numbers out of the air here, but...
Let's say the cypherpunk dream is realized, and everyone on the net uses anonymous mail through a message haven. I believe there are 20 000 000 InterNet users right now. Lets say each person sends one piece of mail every day, and also checks the message haven each day. Each day there are twenty million new messages on the message haven. These are downloaded by twenty million people each day. That's 400 trillion messages that the message haven must send each day. Let's say the average size of a message is 1Kb. This gives a total of 3 Petabits a day. At 86400 seconds in a day, this requires a bandwidth of 30 Terabits/second. This is, of course, far beyond practicality. I'm allso being a little silly here, assuming there is only one message haven for the world. With distributed havens the load on each haven decreases. However, the load on each recieving terminal is the same. Each terminal must process 20 Gigabytes of mail to look for messages to the user. Maybe that'll be practical in a few years, but then again in a few years there will be more internet users.
This scheme is precisely what I described earlier! The two users agree on what to name/tag the file, and that's how they get messages to each other. The problem is Bob can't just retreive that one file (if he is concerned about traffic analysis), so he can get them all so a watcher learns nothing. You have suggested downloading a smaller portion of the available message base instead of the whole thing.
I'm sorry, I must not have read your post carefully enough. I understood there to be no tag outside the encryption wrapper. I thought you were implying attempting decryption of every post on the haven until one worked. My appologies.