[Mailman-Users] Bounce processing questions (feature, or bug?)

[Barry Finkel]

Hank van Cleef <vancleef at lostwells.net> wrote, in part,

>The background scenario is that I have been experiencing the "now you
>see it/now you don't" big-consumer-internet mail service spam
>blocking.  This week it is Verizon.net.  
>
>Basically, mail to verizon.net addresses failed and bounced for a 24
>hour period on the 12th.  Service appeared to have been restored on
>the 13th.  Again, yesterday (the 18th), Verizon quit receiving mail
>again.  The log message being shown by sendmail is of the the form:
>
>Jun 19 10:49:00 julie sendmail[16973]: [ID 801593 mail.info]
>m5JGmxNk016971: to=<customer at verizon.net>,
>ctladdr=<vancleef at julie.lostwells.net> (101/10), delay=00:00:00,
>xdelay=00:00:00, mailer=esmtp, pri=121428, relay=relay.verizon.net.
>[206.46.232.11], dsn=5.0.0, stat=Service unavailable
>
>For the four days June 13-17, mail went verizon.net normally,
>dsn-2.0.0, stat=Sent 
>
>Two Verizon users have contacted me and told me that they had received
>no mail from our list since the 11th; that they had contacted Verizon
>support, and had been told that Verizon was not blocking or dumping
>our list mails.  Both users are sufficiently knowledgeable to have
>looked for shunting to a "spam" or "bulk" file.  I wrote a private
>e-mail to one user giving log details for him to use.  That e-mail
>bounced back sky high, and the bounce message made clear that Verizon
>has a spam block on my IP.  The log message was another dsn=5.0.0
>stat=Service unavailable.

It seems to me that 

     stat=Service unavailable

means that the inbound mailer is not available at the moment.
This should result in a 400-level SMTP retryable reject, not a
500-level hard reject.  The statement

     "Verizon was not blocking or dumping our list mails"

is technically a correct statement; Verizon is not accepting mail.

Another thought comes to mind - when this happens, is Verizon rejecting
all mail, or is that mailer selectively not accepting mail?  If
Verizon is selectively rejecting mail, then I would expect a different
message than

     dsn=5.0.0 stat=Service unavailable.

----------------------------------------------------------------------
Barry S. Finkel
Computing and Information Systems Division
Argonne National Laboratory          Phone:    +1 (630) 252-7277
9700 South Cass Avenue               Facsimile:+1 (630) 252-4601
Building 222, Room D209              Internet: BSFinkel at anl.gov
Argonne, IL   60439-4828             IBMMAIL:  I1004994