Insert a line break in mailto body

I would suggest you try the html tag <br>, in case your marketing application will recognize it.

I use %0D%0A. This should work as long as the email is HTML formatted.

<a href="mailto:[email protected]?subject=Subscribe&body=Lastame%20%3A%0D%0AFirstname%20%3A"><img alt="Subscribe" class="center" height="50" src="subscribe.png" style="width: 137px; height: 50px; color: #4da6f7; font-size: 20px; display: block;" width="137"></a>

You will likely want to take out the %20 before Firstname, otherwise you will have a space as the first character on the next line.

A note, when I tested this with your code, it worked (along with some extra spacing). Are you using a mail client that doesn't allow HTML formatting?

As per RFC2368 which defines mailto:, further reinforced by an example in RFC1738, it is explicitly stated that the only valid way to generate a line break is with %0D%0A.

This also applies to all url schemes such as gopher, smtp, sdp, imap, ldap, etc..

For plaintext email using JavaScript, you may also use \r with encodeURIComponent().

For example, this message:

hello\rthis answer is now well formated\rand it contains good knowleadge\rthat is why I am up voting

URI Encoded, results in:

hello%0Dthis%20answer%20is%20now%20well%20formated%0Dand%20it%20contains%20good%20knowleadge%0Dthat%20is%20why%20I%20am%20up%20voting

And, using the href:

mailto:[email protected]?body=hello%0Dthis%20answer%20is%20now%20well%20formated%0Dand%20it%20contains%20good%20knowleadge%0Dthat%20is%20why%20I%20am%20up%20voting

Will result in the following email body text:

hello
this answer is now well formated
and it contains good knowleadge
that is why I am up voting