COMMAND

    Exchange

SYSTEMS AFFECTED

    MS Exchange 5.5 SP3 + MS Proxy

PROBLEM

    Alan Ramsbottom found following.   If you remote Exchange 5.5  SP3
    SMTP via Proxy 2.0 SP1 then SMTP-TLS won't work.  More  precisely,
    the Internet  Mail Service  desn't advertise  the availability  of
    the STARTTLS command in response to  a client EHLO.  This is  true
    for connections  to the  local or  remote SMTP  port.   Iirc, this
    stuff  did  work  in  the  unpatched  Exchange  5.5  although   it
    advertised TLS rather than STARTTLS in that version.

    Suspect this probably stopped working as a side-effect of the  fix
    for Q237327 "XIMS: Server Advertises STARTTLS Even Though the  SSL
    Certificate  Is  Not  Available".   The  test  boxes used were all
    running SP6A so it's possible (doubt) that's the problem instead.

SOLUTION

    MS identified the problem, which was indeed a regression based  on
    the feature described in Q237327, which disabled the advertisement
    of STARTTLS when a valid certificate was not installed.  A  hotfix
    for the problem described is now available from Microsoft  Product
    Support Services, and  should be a  part of the  next service pack
    release for Exchange 5.5.