I am having trouble figuring out how to set the form to submit a string to an affiliate but also redirecting the user to my own hosted thank you page. I am using the GET method to submit the string.
this is a very dumbed down version of my form
<form action="http://xxxxx.com/api/post.ashx" method="get">
<div>
<label ><span>First Name <font style="color: red;">*</font></span></label>
<input type="text" name="First" value="" maxlength="128" class="form-text required" />
</div>
<div >
<label ><span>Last Name <font style="color: red;">*</font></span></label>
<input type="text" name="Last" value="" size="60" maxlength="128" class="form-text required" />
</div>
<div >
<label ><span>Phone Number <font style="color: red;">*</font></span></label>
<input class="form-text" type="text" maxlength="14" name="phone1" id="phone1" value="">
</div>
</div>
<input class="form-submit" type="submit" id="edit-submit" name="op" value="Submit" />
</div></form>
If I understand your problem right, iframe is a kinda solution here.