router

### router/600_local-config_disposable_aliases
#################################

# This implements supplementary email address aliases which allow
# arbitrary prefixes that are separated from the local part with a
# '.', and an optional counter.  Inspired by Spamgourmet.
#
# e.g.
#
#    foo.stem@example.com   -  the alias 'stem' with a prefix 'foo'
#    bar.5.stem@example.com -  the alias 'stem' again, with a different
#                              prefix 'bar', and a counter 5.
#
# These both route to the same destination(s), as defined in a sqlite
# database lookup from the 'stem' component.  There is a counter
# stored in the database which records how many times each prefix has
# been seen, and the filter either rejects or routes it accordingly.
#
# Initially, unseen prefixes have an (implicit) zero counter, which
# means all email is rejected by default.
#
# If the counter is set to a positive value, then this is decremented
# each time an email is delivered, until it reaches zero, after which
# email to it is rejected and the counter not decremented any further.
#
# If the counter is negative, email is delivered, and the counter is
# not decremented, which means all email is delivered by default.
#
# In cases like the second example address above, the first (and only
# the first) email seen initialises the counter to the value in the
# email prefix, allowing self-limiting email addresses to be
# disseminated.
#
# Finally, the counter can be manually adjusted by control emails to
# the alias in question, so long as the email is sent from a local
# source, or via an authenticated connection.  The subject determines
# the operation:
#
#     !on     - sets the counter to -1
#     !off    - sets the counter to 0
#     !N      - sets the counter to N
#     !report - requests a report email
#
# Other than preceeding or trailing whitespace, the subject must start
# with an exclamation mark, and match one of the above cases.
 
disposable_aliases:
  debug_print = "R: disposable_aliases for $local_part_prefix$local_part@$domain"
  driver = redirect

  # Skip router unless local mail
  domains = +local_domains

  allow_fail
  allow_defer
  allow_filter
  user = Debian-exim
  require_files = DISP_ALIASES_DB
  local_part_prefix = *.
  reply_transport = address_reply
  file = DISP_ALIASES_FILTER