Re: Local relay delivery delays on particular mails

[Nikolaos Milas]

On 8/6/2022 4:57 μ.μ., Viktor Dukhovni wrote:
...
The delay was in processing the message body and/or alerting the queue
manager to the arrival of the new message.  Are you using milters that
query remote oracles (perhaps DNS?) in order to determine whether the
message content is acceptable?  Perhaps there are many URLs in the
message that result in many slow remote lookups?

Thanks Victor for the reply,

Some answers follow inline:

We are not using any milters except the one you mentioned, for DKIM signing.

For your reference, I am attaching (zipped) the whole message from 
wetransfer for which I earlier posted the delivery log (with mail local 
parts changed consistently, and with wetransfer true download links 
scrambled consistently).

You can study the mail content at your convenience.


Jun 08 11:52:48 vmail2 postfix/smtpd[10619]: disconnect from
mailgw1.noa.gr[2001:648:2ffc:1115::27] ehlo=2 starttls=1 mail=1 rcpt=1
data=1 quit=1 commands=7
Either transmission was slow, or body processing (milters, header
checks, body checks, ...) was slow, since the SMTP dialogue ended
late.  If the queue is draining slowly, this could be related to
"inflow_delay" kicking in when message arrival outpaces delivery.

If it is message-related, you may tell from the message source I am 
attaching.

If not, why this phenomenon does not occur with other messages?


smtpd_end_of_data_restrictions = check_client_access
    cidr:/etc/postfix/postfwdpolicy.cidr
Could this be slow?

It's fairly simple:

   # cat /etc/postfix/postfwdpolicy.cidr
   127.0.0.1                   DUNNO
   [::1]                       DUNNO
   195.251.204.12              gwcheck
   [2001:648:2ffc:1115::27]    gwcheck
   83.212.5.27                 gwcheck
   [2001:648:2ffc:126::2]      gwcheck
   62.217.124.2                gwcheck
   [2001:648:2011:8010::213]   gwcheck
   195.251.204.213             gwcheck
   195.251.204.211             DUNNO
   [2001:648:2011:8010::211]   DUNNO
   195.251.204.212             DUNNO
   [2001:648:2011:8010::212]   DUNNO
   194.177.195.36              DUNNO
   195.251.204.238             DUNNO
   [2001:648:2011:10::238]     DUNNO
   195.251.203.238             DUNNO
   [2001:648:2011:3::238]      DUNNO
   10.201.14.48                DUNNO
   0.0.0.0/0                   postfwdcheck
   [::]/0                      postfwdcheck

So, for messages from mailgw1.noa.gr we apply:

   [2001:648:2ffc:1115::27]    gwcheck
   83.212.5.27                 gwcheck

which is:

gwcheck = reject_unverified_recipient, reject_unauth_destination


milter_default_action = accept
non_smtpd_milters = $smtpd_milters
smtpd_milters = inet:127.0.0.1:8891
What does this milter do?

That's for DKIM signing, as I mentioned above.

Any ideas?

Thanks again,
Nick
<<attachment: wetransfer.sample-mod.zip>>