Apple Mail on 10.14.6 auto-adds people's names to email addresses and then refuses to send emails because a name is not a valid address

[izzy0242mr]

I can't send emails because when I copy/paste addresses from a sheet in Excel into the To field (note: these address are JUST the addresses, no names, < > brackets, commas, etc, just one email per cell), Mail automatically adds names to some of the addresses (I guess based on ppl I've emailed before) and then when I click send it gives me errors like: " " is not a valid address or "John Smith is not a valid address". It's super annoying and the only way to get around it is to copy/paste the entire list of emails from Mail's To field into a Word doc, and manually remove all the names it added—but I'm trying to email hundreds of people so that's not a viable option. Any ideas?