What about adding the users to a mail distribution group so that you only send the mail once. Talk to your administrative team or your mail service provider.
100 mails an hour is very slow - I would investigate why this performance is so poor. But 3000 users is a lot of emails. what about posting the PDFs or Excels to a network share (with AD to control access) and letting the users pick up the item from the share. You could send a mail message with the link instead of an attachment.
Also, look at nPrinting (search here for more information).