Mailto and Tel Links in Email Signatures

A tel link wraps a phone number in a link with the tel: scheme, for example tel:+14155550123, so tapping it on a phone opens the dialer with the number filled in. A mailto link does the same for email addresses with the mailto: scheme, opening a new message to that address. Both matter because a large share of email is read on phones, where copying a number by hand is slow and error-prone. Two details make tel links work everywhere. Use the full international format in the link itself, with a plus sign and country code, ideally digits only (RFC 3966 allows hyphens as separators, but not every client handles them), even if the visible text uses local formatting such as (415) 555-0123, because a number without a country code may dial incorrectly for an international recipient. And style the link explicitly, because iOS and some Android clients auto-detect phone numbers and restyle them in blue, which can clash with the signature's design. A mailto link to the sender's own address adds little, since recipients can simply reply, so many signatures leave that line unlinked or drop it. A mailto link to a shared inbox, such as support or sales, is more useful.