Telephone and mail links
A link doesn’t always have to open a web page; it can also be used to send an email or dial a phone number.
To set this up, just use mailto: for emails or tel: for phone numbers in the href attribute of your link.
<a href="tel:+391234567891">Phone</a>
<a href="mailto:info@mail.com,othermail@mail.com">Mail</a>