[Avcheck] hopcount_limit & content_filter

[Michael Tokarev]

A little (and maybe not useful in almost all cases) tip.
When content_filter feature is in use and when reinjecting
goes via smtpd or qmqpd, it may be a good idea to increase
hopcount_limit (default 50) for the receiving smtpd/qmqpd
by one (to be 51).  The scenario is:

  mail accepted by postfix and contains exactly 49 Received:
    headers
  postfix adds another Received: header by it's own, making
    50 headers total
  mail goes to content_filter and received by smtpd which
    counts number of Received: headers and refuses to accept
    message saying "too many hops".  But at this stage,
    this extra hop is internal to the local mailsystem and
    should not be counted.

The funny thing here is that most other systems will not
accept such email anyway (if memory serves me right, default
hopcount_limit for Sendmail is 25).

/mjt