Peer,
> If reinjection of mail fails, Amavis will send a DSN back to the sender to
> notify him about this failure.
>
> But if D_REJECT is active this leads to *2* DSN back to the user: One DSN
> from the sending MTA (because Amavis blocks that mail to the feeding
> MTA), second DSN from Amavis himself.
A bug. Either a reject or a bounce should happen, not both.
As Thomas said, it was not envisaged to have a back-end MTA reject
mail at this late stage, so the situation was not thoroughly tested.
> In my understanding Amavis should not send his own DSN in case of D_REJECT
> if the mail has been already rejected against the feeding local MTA (and
> in case of Postfix' smtpd_proxy_filter also against the external sending
> MTA).
Note there is no dedicated configuration variable to configure what should
happen when a back-end MTA does not want to accept a message. Luckily there
is a %final_destiny_by_ccat, which allows to assign a 'destiny' to
a CC_MTA case:
%final_destiny_by_ccat = (
CC_VIRUS, sub { c('final_virus_destiny') },
CC_BANNED, sub { c('final_banned_destiny') },
CC_SPAM, sub { c('final_spam_destiny') },
CC_BADH, sub { c('final_bad_header_destiny') },
CC_MTA.',2', D_REJECT, # in response to 5xx from MTA
CC_OVERSIZED, D_BOUNCE,
CC_CATCHALL, D_PASS,
);
This should have sufficed, had it not been for a bug which
forgets to set $r->recip_destiny in case of a MTA reject.
The following patch fixes it (applicable to 2.6.4). It is more
extensive than it need be, because it also makes possible to
obtain a reject text from a %smtp_reason_by_ccat, which was
introduced in 2.6.4. Also, as the D_PASS does not make any sense
in case of a MTA failure (we can't forward anyway, even though
we want to), the patch silently turns a D_PASS into a D_REJECT
for the CC_MTA case, so adjusting %final_destiny_by_ccat is
not really necessary, it's just nice to be explicit.
--- amavisd.orig 2009-06-25 14:39:01.000000000 +0200
+++ amavisd 2009-07-10 19:55:58.000000000 +0200
@@ -1493,4 +1493,5 @@
CC_SPAM, sub { c('final_spam_destiny') },
CC_BADH, sub { c('final_bad_header_destiny') },
+ CC_MTA.',2', D_REJECT,
CC_OVERSIZED, D_BOUNCE,
CC_CATCHALL, D_PASS,
@@ -11317,4 +11318,30 @@
$msginfo->blocking_ccat($blocking_ccat)
if !defined($msginfo->blocking_ccat);
+ my($final_destiny) =
+ $r->setting_by_contents_category(cr('final_destiny_by_ccat'));
+ if ($final_destiny == D_PASS) {
+ $final_destiny = D_REJECT; # impossible to pass, change to reject
+ }
+ local($1,$2);
+ $r->recip_destiny($final_destiny);
+ if ($final_destiny == D_DISCARD && $smtp_resp =~ /^5/) {
+ $smtp_resp =~ s{^5(\d\d) 5(\.\d\.\d)}{250 2$2}; # 5xx -> 250
+ }
+ my($smtp_reason) = # get the custom smtp response reason text
+ $r->setting_by_contents_category(cr('smtp_reason_by_ccat'));
+ $smtp_reason = '' if !defined $smtp_reason;
+ if ($smtp_reason ne '') {
+ my(%mybuiltins) = %builtins; # make a local copy
+ $smtp_reason = expand(\$smtp_reason, \%mybuiltins);
+ $smtp_reason = !ref($smtp_reason) ? '' : $$smtp_reason;
+ chomp($smtp_reason); $smtp_reason = sanitize_str($smtp_reason,1);
+ $smtp_reason = substr($smtp_reason,0,100) . "..."
+ if length($smtp_reason) > 100+3;
+ }
+ $smtp_resp =~ /^(\d\d\d(?: \d\.\d\.\d)?)\s*(.*)\z/;
+ my($dis) = $final_destiny == D_DISCARD ? ' Discarded' : '';
+ $r->recip_smtp_response("$1$dis $smtp_reason, $2");
+ $r->recip_done(1); # fake a delivery (confirm delivery to a bit bucket)
+ # note that 5xx status rejects may later be converted to bounces
}
$msginfo->header_edits($hdr_edits); # restore original edits just in case
@@ -17775,10 +17802,10 @@
sub enhance_smtp_response($$$$$) {
my($smtp_resp,$am_id,$mta_id,$dflt_enhcode,$cmd_name) = @_;
- local($1,$2,$3); my($resp_shortmsg,$resp_msg);
+ local($1,$2,$3); my($resp_msg);
my($resp_code,$resp_enhcode) = ('451', '4.5.0');
if (!defined($smtp_resp) || $smtp_resp eq '') {
- $resp_shortmsg = 'No resp. to '.$cmd_name;
+ $smtp_resp = sprintf('No resp. to %s', $cmd_name);
} elsif ($smtp_resp !~ /^[245]\d{2}/) {
- $resp_shortmsg = 'Bad resp. to '.$cmd_name;
+ $smtp_resp = sprintf('Bad resp. to %s: %s', $cmd_name,$smtp_resp);
} elsif ($smtp_resp =~ /^ (\d{3}) [ \t]+ ([245] \. \d{1,3} \. \d{1,3})?
\s* (.*) \z/xs) {
@@ -17787,9 +17814,7 @@
if ($resp_enhcode eq '' && $resp_code =~ /^[245]/)
{ $resp_enhcode = $dflt_enhcode; $resp_enhcode =~ s/^\d*/$c/ }
- $resp_shortmsg = $c eq '2' ? 'Ok' : $c eq '4' ? 'TempFailed' : 'Failed';
}
- sprintf("%s %s %s, id=%s, from MTA(%s): %s",
- $resp_code, $resp_enhcode, $resp_shortmsg,
- $am_id, $mta_id, $smtp_resp);
+ sprintf("%s %s from MTA(%s): %s",
+ $resp_code, $resp_enhcode, $mta_id, $smtp_resp);
}
The range of choices is now fully supported through
the $final_destiny_by_ccat{(CC_MTA)} setting, i.e.
D_REJECT, D_BOUNCE and D_DISCARD. Usually one would chose
a D_REJECT or D_BOUNCE.
Note that even when a D_REJECT is chosen as a final_destiny_by_ccat
for the CC_MTA case, it can still happen that amavisd responds with
a 2xx smtp status and sends its own bounce. This can happen with
multi-recipient mail, where some recipients are accepted and some
rejected by MTA. As SMTP protocol does not allow for per-recipient
responses, we have no other choice but to accept a message and
send a bounce to the rejected recipients, while delivering to the
accepted recipients. So, late header checks are alright, but late
per-recipient restrictions are to be avoided.
Mark
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