The original standard for mailto: links, RFC 1738, says this:
A mailto URL takes the form:
mailto:<rfc822-addr-spec>where
<rfc822-addr-spec>is (the encoding of an)addr-spec, as
specified in RFC 822 [6].
Under that definition, addr-spec is of the form “local-part@domain”, so no proper name could be included.
But the mailto: section of RFC 1738 was first superseded by RFC 2368, which allows (among other things, including predefined subject lines) for an RFC 822 mailbox specification—which includes a proper name.
[2016-05-31] As David Balažic points out in a comment, RFC 2368 is in turn obsoleted by RFC 6068. From Section 9, “Main Changes from RFC 2368”:
The main changes from RFC 2368 are as follows:
- Changed syntax from RFC 2822
<mailbox>to [RFC5322]<addr-spec>.
An RFC 5322 <addr-spec> is of the same “local-part@domain” form as mentioned above, so once again, no name can officially be included.
In actual use, mailto:Fred Foo<foo@example.com> still seems to work, but it’s not officially supported; you may also have to encode the space, i.e., mailto:Fred%20Foo<foo@example.com>, and/or put the name in quotes, i.e., mailto:"Fred Foo"<foo@example.com>.