At 02:27 PM 2/18/98 +0000, T.G.Griffiths@exeter.ac.uk wrote:

Mark@unicorn.com makes a good point about MailGuard. If A and B both run MailGuard, and neither is on the other's allowed list, do you get an infinite bounce when A mails B or does the prog. get around it? I can think of a couple of ways, but what does MailGuard do?

The classic implementations of systems like that do one of three things 0) Don't think, leading to infinite mailbounces (often caught in testing, since it's very bad.) 1) Prevent loops, but there's no way to communicate 2) Prevent loops, and recognize mail from other MailThingies, which makes it easy for Spammers to forge. If you get fancy, you can probably work something like Receive message Send and record Alice-cookie -> <-- Reply with Alice-cookie and new Bob-cookie verify Alice-cookie and accept message Reply to Bob-cookie --> Verify Bob-cookie for future use Thanks! Bill Bill Stewart, bill.stewart@pobox.com PGP Fingerprint D454 E202 CBC8 40BF 3C85 B884 0ABE 4639