Issue Summary

A subscriber can have an email address that begins with a non alpha-numeric character as long as it is in this list of special characters permitted in email addresses:"!#$%&'*+-/=?^_`{|}~;". Examples of this would be: $money@example.com , #hashmaster@example.com , and %profits@customer.example.com 

While these emails can be added to an Audience Specific page as users, they can't subscribe to Audience Specific pages as the email validation for subscribers is more restrictive than the RFC and will reject email subscriptions where the address starts with a special characters

Steps to Reproduce

1. Create an Audience Specific user with an email #something@example.com (Example.com is an IETF-approved testing domain)
2. Assign this use to some components and/or groups.
3. Preview your audience-specific page as this user
4. Attempt to subscribe to the page via email

Expected Results

This user will be successfully subscribed to receive email notifications at #something@example.com 

Actual Results

A banner error will appear at the top of the page

Please enter a valid email that you wish to have updates sent to. 

Workaround

Currently, there is no known workaround for this behaviour.

Clicking Subscribe this user when creating a user who's email starts with a special character does NOT bypass this issue, and the user will not be subscribed.