Bug: can't find customers if their email address contains a dash

[slaFFik]

So, the customer has the - in their email address.
The system sends a request to the side and it's processed though EDD Helpscout plugin.

EDD Helpscout does not find a user when their email contains a dash.

Example: a-user@example.com.

Same problem in both HelpScout and FreeScout.