Strange error in mailto field

Hi,

I set up a CF7 form to register devices requests, as far as I can see it works fine, but I get this strange syntax error on the “to” email field currently populated with :
“[hidden-username] <[hidden-useremail]>”
I can cofirm tha the email is sent ok, but I would like to understand why I get an error in the interface.

Thanks for your time
Thierry

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