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Re: mailing list software, was What does the mailsig mechanism mean?

2004-11-01 17:43:26

At 04:20 AM 11/1/2004 +0000, John Levine wrote:
The third category [Freeware like Mailman, Sympa, and Majordomo] is most 
difficult.  People tend to install the freeware packages and forget about 
them, so it'll be a challenge to get them to upgrade, unless they're behind a 
mailsig-aware MTA that handles the signatures automagically.

I'm a little worried about the mailing lists that are behind a mailsig-aware 
MTA, actually.  
What should mailing lists do about messages they sent which arrived without a 
signature?  I can think of 3 options:

1. Block them
2. Accept them and send them to the list without a signature from the list
3. Accept them and sign for the list

I don't expect option 1 will be practical anytime soon.

2 seems promising; it seems only appropriate to sign if the input was signed.

3 sounds like a recipe to dilute the value of the list's signature, and seems 
like a good way to get messages signed by the list for use in a subsequent 
replay attack.  Of course, this would be more reasonable for closed lists.

A mailing list behind a mailsig-aware MTA will tend to behave per option 3 by 
default.

-Jim


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