> >If you are getting the "552 Too Many Recipients" message, it is likely =
> that Listserv is pruning what it thinks are non-functional addresses, =
> since the mail server should abort the transmission when it gets that =
> number.
>
> LISTSERV does not arbitrarily delete addresses.  It does so only on the basis of
> the actual error message reported by the mail server.  With many mail servers,
> an aborted transmission is resumed and the messages are eventually delivered.

The proper response to this error is for the sending SMTP server to send
the rest of the recipients in a separate copy of the message.   The receiving
SMTP server should have accepted the recipients up to the point of the error.
It's true that the SMTP standard requires the receiving SMTP to accept at
least 100 recipients per copy of a message, but the same situation would
occur should the sending SMTP server send more recipients than that.