There is a module that allows email addresses to be optional during registration. This module is not supported; test extensively before using!
Visit Admin > Configuration > People > Account Settings (SITENAME/admin/config/people/accounts)
Check BOTH of the "Enable optional email..." boxes in the "OPTIONAL MAIL ON REGISTER SETTINGS" section, as shown.
You can choose to make the email field optional, visible-but-disabled, or hide it completely. You should probably leave the default "Leave the email field visible and editable" option selected.
Scroll down and click the Save button to save your settings.
- From the user perspective (meaning, not logged in as admin), you'll register two brand-new accounts for your programs, one that uses an email (such as a colleague's personal Gmail address), and one that doesn't use an address.
- For each of the accounts, log out after your initial signup, then log back in to make sure you can log in.
- For the account with an email, try to use the "reset password" feature and make sure it works.
- For the account without an email, try to use the "reset password" feature and make sure your site doesn't blow up.
- Discuss an alternative process/policy with your teammates about how to help/support/reset passwords for the users without email addresses.
If you have problems and want to go back to mandatory email, please let us know. Otherwise, we'll presume that you're happy with optional email.
As a *very* simple alternative, we can instead try to override the signup form so it says "Don't have an email address? Use email@example.com instead!" and you'll just have them enter a dummy address.