How can we improve WHMCS?

We have a lot of clients that don't understand that email can be set in WHMCS for some administrative notifications and in hosting account for some other technical notifications. Most clients never updated their email in hosting account and they beleive that changing email only in WHMCS is enough. Now we have a lot of hosting accounts with obsolete and even non existant email addresses, and lot of important notifications from servers are sent to invalid emails.

I would suggest to add optional feature (checkbox) on client and admin side right under the client email field, on client details page - "Update email address at all hosting accounts and other applicable services" or something similar (checked by default), so that staff or clients can be able to easily update email on all applicable services when changing email in WHMCS.