[exim] exim / vexim install and limiting mails per minute / …

Hi
I have exim installed and using the mysql/php admin interface vexim
for configuring users and domains.

I have had a request as to whether or not I can limit the out bound
email for a user / domain on a per minute / hour / day. Can this be
done ? and can it be done in the following ways, when , the user and
/ or domain has reached the limit, 1) reject the connection from the
user
with error message, 2) simply que the mail and release it as per the
users limit ?