Have you looked into the error.log, if something went wrong. OpenACS allows queued and immediate sending of mail messages. You might check, whether the mails are in your mail queue (
select * from acs_mail_lite_queue).
For sending multiple messages, look at the bulk-mail package. The package has just a minimal www interface, but can relative easily used via the api [1]. For an online-documentation, see [2]. When installed, you find all calls via the api-browser in your installation. When using dotlrn, you can consider the bulkmail portlet (bm-portlet)
Hope, this helps
-gustaf neumann
[1] https://openacs.org/forums/message-view?message_id=284507
[2] https://openacs.org/forums/message-view?message_id=32498
