By 'normal' form I take you mean <form> instead of <cms:form>, right?
Assuming that is correct, thing is that <cms:form> needs to be the parent of all Couch managed fields for them to function as expected.
However, normal inputs (e.g. plain <input> and not <cms:input>) can also be placed within <cms:form> and they should work just the same as under a normal <form>.
So, you may try replacing <form> with <cms:form> expecting backward compatibility.
That said, you mentioned you are using a normal form because it needs to work with PHPMailer.
I wonder if you missed noticing that PHPMailer now ships as a native addon with Couch (viewtopic.php?f=5&t=10750
Please see if what you are trying to do can be done using the addon.
Hope this helps.