Bug#807258: sendmail: Strange DSN code returned by sendmail with greylisting

[BERTRAND Joël <joel.bertrand@systella.fr>]

Source: sendmail
Version: 8.15.2-2
Severity: grave
Justification: renders package unusable

Dear Maintainer,

I use for a long time a sendmail configuration with debian clamav and
spamassassin milters and a customized milter greylist (same sources that
debian's milter but with some different compilation options).

I have checked in greylist-milter sources and milter returns 451 4.7.1 DSN by
default. My configuration ran like a charm for a very long time.

I have recently upgraded my mail server and I have seen that last sendmail seems
to change DSN code. For example, I have tried to send a message from an external
SMTP server. It receives :

550 <joel.bertrand@systella.fr>... 451 4.7.1 Greylisting in action, please come back later

I don't understand why milter-greylist returns 451 and why sendmail changes this
error to 550 since last sendmail upgrade.

I have checked sendmail.cf file and I haven't found what could change this DSN
code.

I don't know how investigate.

Regards,

JKB

-- System Information:
Debian Release: stretch/sid
  APT prefers testing
  APT policy: (990, 'testing'), (500, 'unstable'), (500, 'stable'), (1, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 4.2.0-1-amd64 (SMP w/4 CPU cores)
Locale: LANG=fr_FR.UTF-8, LC_CTYPE=fr_FR.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)