Emails - fix duplicate email error

Summary: $email => $e_email. Fixes T5933.

Test Plan: Added an email that was already on another account and got the proper "Duplicate" UI with the duplicate email address still entered

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: epriestley, Korvin

Maniphest Tasks: T5933

Differential Revision: https://secure.phabricator.com/D10334