There are several different Sign Up for a Free Gift patterns, but here is the basic pattern we're trying to create;
And there are many variations on this.
We'll look at 2;
Rather than delivering X in the email, you can give a link to X, which goes back to a Gift Page on your site.
This is the same, but now the Gift Page is behind a password wall. You give the password, and the link in the email.
Which one you choose will depend on;
“Should I use proper logins?”
In this flow, passwords and logins and account registrations and email verifications are too interruptive to make the UX flow work. They also don't add value, because once Bob's gotten X, what does he now need a login for?
Go as simple as possible, for your use case.
There is of course a legitimate business goal here- if you goal is to get people to sign up for a membership ( PAID or FREE ), than this is exactly the path you'll want to take.