Some keys have User IDs that are just raw e-mail addresses, like
"firstname.lastname@example.org". searching for those keys "by e-mail address" using angle
brackets as specified by the gpg documentation fails, but i think it should work.
While this is an "addr-spec" from RFC 5322  and not the "name-addr"
recommended by RFC 4880 , it's something people are used to seeing in the
same location (the e-mail "to:" or "from:" fields)
the man page says:
By exact match on an email address. This is indicated by enclosing the email address in the usual way with left and right angles. <email@example.com>
a User ID that is an exact match on that e-mail address should also be returned
in the list of matching keys.