[jQuery] $.post cross domain first sends an OPTIONS verb?

[jQuery] $.post cross domain first sends an OPTIONS verb?


I use $.post like so:
$.post("http://mydomain.com/some/webservice", $.toJSON({ emailAddress:
emailAddress }), callback, "json");
this works great..the response of the POST is a json string and that
is used in the callback..now I added https:
$.post("https://mydomain.com/some/webservice", $.toJSON
({ emailAddress: emailAddress }), callback, "json");
so it is now a cross domain post...in firebug I see that instead of
POST'ing like in the http case..it first is sending an OPTIONS
verb..why? The webservice doesn't know how to respond to that and
gives a 403 forbidden...I need it to just send the POST like it did
when it was on the same domain...
Any insight?