I am adding custom options like
$sub = array("EmailAddress" => $testEmail,
"Name" => "Test Mail",
"CustomFields" => array(
"Resubscribe" => true);
and in campaign body I am using it like :
copy [link] in your browser. [link] should be replaced by http://www.google.com but not done. Can you please tell me what wrong I am doing??
Sorry for my poor English.
That's odd - I can't really see why that wouldn't work, assuming the custom field value is being added correctly and all lists added to your campaign have a "link" field.
However, it is typically safer to drop the protocol (http://, https://, etc.) from the custom field value, and hard code it in your HTML instead.
<a href="http://[link]">Your link text here</a>
If that isn't working for you though, could you send us your account URL and an example draft, so we can have a look?