Problem with forwarders in forms via webmail

This is not specifically a Rapidweaver issue, but it springs from a RW site using Super Forms 2, which requires that forms be emailed via the host server—( Therefore, webmail is a given.

For their own reasons, several of the targets/recipients of such forms will not use webmail, so I have established forwarders which redirect to mary@hotmail etc. All of which are working except, it seems, one. There’s always one.

I have not received a bounce, or error message, regarding the ones that my target lady claims she has not received.

All the other recipients found their forms in the junk folder, but she claims to have ‘searched every folder’ to no avail. (She lives some distance away from me. Otherwise I’d brain her.)

I established a second forwarder on the mail account, so that it forwards the forms to her, and to me. The extra forwarder (to me) is working.

So, I set up a third forwarder— to a non-existent account, which is, indeed, non-existent, to see whether I would have been sent an error message. No error message is apparent.

I’m pretty sure that the missing forms will be in one of her ‘folders’.
Is there a way to determine from the webmail interface whether those forms were delivered to her?

Thanks in anticipation,