Yo Ra,
>I have a mailing list of about 3600 members (recipients per message: 160).
>Some users have not been receiving the postings to this list. I then
>looked at the logs for the latest message and it looked like almost 800
>members did not get the mail. I am assuming that the email of each
>recipient will show up in the log in the "dialog" smtp has with the remote
>mail hosts.
yes, you must see a
RCPT TO:<listrecipient@recipientdomain>
for every list member.
>I could not find the email address of the user that originally
>complained not receiving the postings in the log.
>
>Vast majority of the missing postings seems to be to the hotmail users -
>more than half of the hotmail users are not getting the mail.
I had a pb with Earthlink and a Listar list server I built for an IMail
admin. After a certain number of msgs from one ip, Earthlink then
blackholes that sending ip address by bouncing all further mail from that
ip as <unkknown>, while telnetting to Earthlink�s MX from another ip
succeeds in delivering to the "unknown" user. But unlike your case, we see
these send attempts and bounces in the postfix logs and log summary.
>IMail/SMTP seems to sort the 160 recipients and if there are multiple
>recipients at the same domain it is using some kind of "multiple" send, with
>a max value of 5.
This makes sense, to avoid making 160 distinct SMTP sessions to the same
MX. But spammers and harvesters and mailbombers use the "multiple
recipients per SMTP session", also, so mail servers can usually be setup to
limit how many msgs they send and receive in some session. As Scott said,
5 is very low and should�t trigger blackholing.
>So if there are 20 hotmail users, it is sending four
>mails with 5 users per "SEND" to the hotmail domain. Could this be the
>source of the problem ? Could hotmail be rejecting this kind of send as
>anti-spam ?
They could be, but you should see the attempts by your server, and
Hotmail�s rejects in your mail logs.
>I am not a SMTP expert - this could be a standard feature, the
>reason I am suspecting is I see the missing mails in this multiple sends.
>
>If you would like to know any settings, imail logs, please let me know.
A key item you haven�t told us is what is the status of Imail�s queue? If
you can�t find the list member�s names in the Imail logs, then maybe the
msgs are stuck in Imail's phunckee queue.
Len
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