can i tell if email accounts are being actively used?

[johngute]

i've been acepted for a beta test for gmail for your domain!

but i have about 6 email accounts and i'm not sure if people are using them,
i've emailed them all, but besides disk usage, is there any other way to see if these accounts are being used activley?

[Grunfeld]

check quota daily or twice a day, send them a big e-mail or turn them off you will then know for sure..