Risk with FEATURE(nouucp)
UUCP addresses are those that use a ! character to separate
address components. For example, the following
address says to send the message first to the host
hostA, and then
hostA will relay that message
to the user at hostB:
hostB!user@hostA
If you have tuned your site to prevent unintended
relaying, misuse of the nouucp feature can open your site to an
unexpected form of relaying.
Consider a workstation on your network that forwards
all its mail to the central mail hub using LOCAL_RELAY (LOCAL_RELAY mc Macro on
page 604) or LUSER_RELAY ($L
on page 832). If that workstation also
defines:
FEATURE(`nouucp', `nospecial')
addresses containing the ! character will not be recognized as
special and will be forwarded to the mail hub as
is.
If, on the mail hub, you forget to declare the
FEATURE(nouucp), the as-is address
forwarded to it will be
recognized as special. Because the address was
received from an internal workstation, relaying is
allowed. The !
address will have the hostA
part stripped and the result will be relayed to
user@hostB.
Thus, it is a good idea to define nouucp on the mail hub
if you define it on any of your workstations.
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