I have previously used sendmail from the command line to send a large number of messages and used the -odd flag to defer delivery so that the program puts the emails into the queue quickly and returns to the user while messages are delivered in the background. This is described in the DeliveryMode portion of the man page:
http://www.sendmail.org/~ca/email/man/sendmail.html
The new server I am moving to is using exim and sendmail is aliased to exim, and is choking on the -odd flag. Is there a way to force exim to perform a deferred delivery on a message from the command line and put it into the queue instead of immediately trying to deliver it?