As others have noted, this is a neat-looking solution but breaks a lot of things. In addition to copy/paste:

* Middle-clicking to open my webmail in a new window

* “Right-click > Copy link address” because my browser doesn't know about my email client

* Possibly screen readers (I don’t know this one for certain)

* Keyboard accessibility: I can tab onto the link, but Enter doesn’t activate it

* Probably some other things I haven’t thought of

Since you’re requiring JavaScript anyway, here's a better solution that doesn't decrease resistance to scrapers¹ and fixes the above problems by turning all of your .cryptedmail tags into proper links that work the way users expect them to.:

    document.querySelectorAll('.cryptedmail').forEach(a => {
        const email = `${a.dataset.name}@${a.dataset.domain}.${a.dataset.tld}`
        a.href = `mailto:${email}`
        a.innerText = email
    })

¹If they’re running JS, they can also just tell Selenium to intercept navigation and then click every link on the page.