a:link.postlink, a:active.postlink, .postlink {color: red;}

a:link.postlink, a:active.postlink,a:visited.postlink, .postlink {color: red; text-decoration:underline}

return "<a href=\"".$Link."\" target=\"_blank\">{$matches[3]}</a>";

return "<a href=\"".$Link."\" class=\"postlink\" target=\"_blank\">{$matches[3]}</a>";

a:hover { color: #465584; text-decoration:underline }

a:link.postlink, a:active.postlink, .postlink {color: red;}

a:link, a:visited, a:active { text-decoration: underline; color: #000 }
a:hover { color: #465584; text-decoration:underline }

a:link, a:active { text-decoration: underline; color: #000 }
a:visited { color: #0033FF; text-decoration:underline }
a:hover { color: #ccff00; text-decoration:underline }