Hi, no, the length of a standard field can't be changed from an extension, the 80 characters stay. A new custom field would mean pointing all the email functions to it, not worth it.
Standard has a better place. On the Customer Card open Document Layouts. There you set per document type, invoice, order confirmation, statement, a Send to Email field, and it's much longer, 200 characters as far as memory serves. Several addresses go in with semicolon, and you can also pick them from the customer's contacts. BC takes that address first when the document is sent.
For CC, the email editor has CC and BCC already, so by hand it works. Automatic CC needs a small extension.
Glad to help - follow up if anything is unclear.
► If this solved it, marking it verified helps others too.
Regards,
Grigorios Mavrogeorgis
Business Central Consultant & AL Developer
Work: Gmsoft Limited
Blog: insidebusinesscentral
LinkedIn: linkedin.com/in/gregorymavrogeorgis