<a class="css-email" data-email="info"></a>

.css-email {
text-decoration: underline;
cursor: pointer;
}
.css-email::before {
content: attr(data-email);
}
.css-email::after {
content: "@elastik.eu";
}

<script>
document.addEventListener('DOMContentLoaded', function() {
const emailSpan = document.querySelector('.css-email');
emailSpan.addEventListener('click', function() {
const email = this.dataset.email + '@elastik.eu';
window.location.href = 'mailto:' + email;
// alert("click");
});
});
</script>