Ipn Paypal how to add other optional fields?

I need to add three additional optional fields to the return email after the purchase: place of birth, date of birth and fiscale code.
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Who can advise me how to do it?
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Save the data to your payment database table before you redirect to PayPal.
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Also I think the Options are supposed to be for example things like "Small, Medium, Large". Either way, your {data:blahblah} should go in Option x VALUE and then in Option x NAME you would put e.g. "Contact Phone Number"

Once saved the data in the db will these also appear in the purchase email made? Are you telling me this ?
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For the question of optional fields I agree.
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But in the custom parameter entry, in fact, what should be inserted, could it correspond to the custom field of PayPal's varibiali? Thank you

Okay well no. Midnight here remind me in 8 hours I'll think about it more

I did not understand you, did you mean this?
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Excuse me if I write here, but I wanted to ask once saved the data in the db will these also appear in the purchase email made?

If you include it in the email with shortcodes then yes, use {data:field_name} in the email body!
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Best regards