I would like to know if it's possible to provide an email certificate (signed by a recognised CA) so the user clicking on the mailto link can send encrypted email to the owner of the cert ?
<a href="mailto:[email protected]">[email protected]</a>
Is there any way to do that using the mailto link or using some JS ? Given the mailto link is handled by a local email client, should be possible ?
If there is no direct way to do this, how to make it?
You can look up what you according to the current specification can do with a mailto URL in RFC 2368. You'll see that it only refers to the construction of the mail text and headers, not their encoding or encryption. There may be extensions for some mail clients, but that's not something one should generally count on.
Furthermore, Web mail users generally will have problems with such links anyways. Thus, for a solution that has to be usable by anyone, a scheme counting on some client side program is not a good choice.
Thus, some Web form as mentioned by @Eugene accessable only via https would best serve your requirements.