[Mailman-Users] Not all subscribers receiving list mail.

Mark Sapiro msapiro at value.net
Thu May 11 06:21:51 CEST 2006

Bryan Daniel wrote:
>We attempted three different times to send to one of these lists and
>the result was the message going to the same people from the list each
>time.  If this were caused by a disconnection problem with the MTA, I
>would expect perhaps a different subset of subscribers would not get the
>messages on each occasion.

Not necessarily. The recipient list is calculated (and it's in a hashed
order, so it's not alphabetical). In delivery, it is then sorted by
domain and chunked into pieces of size SMTP_MAX_RCPTS (default 500).
Then, a connection is opened to the SMTP server, and the message is
sent in 8 or so transactions of 500 RCPTs each, and the connection is

The MTA may not like 500 RCPTs per transaction in which case you need
to reduce SMTP_MAX_RCPTS in mm_cfg.py. It may not like a number of
large transactions on a single connection in which case you need to
set SMTP_MAX_SESSIONS_PER_CONNECTION to some non-zero number in
mm_cfg.py. The default setting is zero which means all chunks will be
sent on a single connection. A non-zero setting (1 or 2 or so) means
send that many chunks, then disconnect and reconnect befor sending
that many again until done.

Mark Sapiro <msapiro at value.net>       The highway is for gamblers,
San Francisco Bay Area, California    better use your sense - B. Dylan

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