Don't add 'mailto:' to email addresses automatically in interactive proofing

[#1]

When QCing emails in the proofing tool our unsubscribe link as the recipient email included in the URL. The proofing tool currently adds mailto: in front of any url that contains an email address.

This doesn't make sense because it makes links that are built correctly appear broken and could potentially show things as linked that aren't. Seems like a design flaw to make any changes to assets in the proofing tool as these won't be reflected in the actual files.