excellent feature, but a question...

I really need this feature for a school website:
Older children will use their email address, but some may choose not to for
privacy reasons, and younger children shouldn't need to have an email at all.

This module looks like it could solve my problem.

However, what happens if I enable the core 'contact' module (so that those
who choose to provide their email can be mailed by teachers)? Will the
contact module crash or do something unexpected if the recipient hasn't got
an email address specified? I mean, by default the contact module doesn't
*have* to check, because *all* accounts will have an email address. So
does 'local email' module affect the 'contact' module?

Cheers.