feat(form): disallow email address as first name

[mathetos]

User Story

As a site admin, I want to disallow email addresses from being used in the name field so that spam is reduced.

We still get spammy donors despite several measures we've taken. But an easy thing we could also do is simply add a validation check on the first name to prevent an email address from being used there.

Current Behavior

I currently see email addresses submitted in the name field, which indicate spam.

Expected Behavior

I expect to see Give prevent these spammy submissions.

Possible Solution

Check for the presence of an @ character in the First Name and Last Name fields and prevent submission.

Steps to Reproduce

1. Create a new form with default settings.
2. Enter fake email address test@example.com into the First or Last Name fields.
3. Attempt to submit form.

Visuals

Tasks

• Detect email in name fields using is_email() in server-side PHP validation.
• Display notice: <First Name|Last Name> cannot contain email address.

[kevinwhoffman]

@Sidsector9 I built out the issue that @mathetos started so you can tackle this in the next sprint. Please ensure you validate both client-side and server-side.

[mathetos]

@kevinwhoffman We could just use the WordPress core function is_email to validate whether the name field is formatted like an email address, instead of only searching for the @ character. That's how I implemented that in the Stop Donor Spam addon:
https://github.com/mathetos/Stop-Donor-Spam/blob/master/stop-donor-spam.php#L95-L99

[kevinwhoffman]

@mathetos Good suggestion.

@Sidsector9 I've updated your Tasks to only require server-side validation with is_email(). Don't worry about client-side as I don't expect many real users to be entering emails into the name field, and even if they do, it would be caught server-side.