We switched our license to a Full Domain Mode license.
Can I still use my account to authorize emails that do not belong to our email domain?
Yes, you can add emails from other email domains, just like you did with the classic license.
The only remark is that emails from other domains cannot become dormant users, so you will be paying for their license until the moment you remove them from your account. With the Domain Mode license, only emails from the authorized domain can enter the dormant state.