'Today' considers data retention and IMP

[Chris Edwards]

On Tue, 13 Jan 2009, Ian Batten wrote:

| Typically?  I see more and more SMTP servers doing opportunistic TLS these
| days.  If you turn on TLS without worrying about certificates being checked
| (which is after all dealing with a different risk) you'd be surprised at how
| much TLS you end up doing to all sorts of people.

Yep - I too notice the opportunistic TLS on my private box getting used 
more.  However, $workplace doesn't currently support this, since 
historically:

(1) Admins of large MTAs told us there's plenty sites out there with 
    broken TLS implementations, and that they found debugging the 
    resulting interoperability problems got tiring quickly...

(2) I'm not convinced the certificate check IS dealing with a different
    risk.  The very people most likely to have the ability to passively 
    sniff *backbone* links are probably ISP staff, who could just as easily 
    mount an active attack to defeat opportunistic TLS.  E.g redirect SMTP
    to a transparent proxy, effectively man-in-the-middle'ing the TLS.

Anyway, that's the historic rationale.  But now, it seems quite likely any 
IMP black boxes will be passive, so opportunistic TLS would be sufficient 
to keep the data private....

Note - all the above is specifically discussing mail server<->server traffic.