What email encryption is actually in use?

[Steven M. Bellovin]

In message <20021002181118.GG5461 at ralph.worldwinner.com>, John Saylor writes:
>Hi
>
>( 02.10.02 12:50 -0500 ) Jeremey Barrett:
>> but it's always better to encrypt than not, even if no additional
>> trust is gained.
>
>While I generally am on board with this, I can see a situation where the
>encryption overhead [and complexity] may be excessive [underpowered mail
>servers administered by beginners] compared to the gains. 
>

The primary use of STARTLS for SMTP is for mail *submission*, not 
relaying.  That is, when clients (like Eudora) generate mail, they 
submit it to an ISP or organizational SMTP server.  If this server is 
accessible from the Internet, it should require some sort of 
authentication, to avoid becoming an open spam relay.  This is 
sometimes done by a password over a TLS-protected session.

In other words, this isn't opportunistic encryption, and doesn't run 
into the problem of "random smtp server has a self-signed cert".  The 
client should be configured to know what cert to expect.

		--Steve Bellovin, http://www.research.att.com/~smb (me)
		http://www.wilyhacker.com ("Firewalls" book)



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