Sugar 7.1.5 Bug
Working in Sugar CRM 7.1.5, I have encountered a bug. Filtering on email address is not applied on list view. I was also not able to search on email field by using REST endpoint <REST_URL>/Leads/filter.
This bug is reported on https://web.sugarcrm.com/support/issues/ with the following bug number:
Subject: Not Able to Filter by Email Address in Listview
With the latest version 7.2.0 this issue has been resolved.