I'm not able to send emails from my Hotmail account using Mail app

If you can’t send or receive email on your Mac

If Mail on your Mac keeps asking for your password

• Your email provider needs you to update or reset your password for security reasons. For example, if you're using Google’s two-step verification, your Gmail account in Mail requires the appropriate app-specific password.

You are thinking about resolutions and I congratulate you. Here are my thoughts. You can move any emails you want to save to a new (or existing) local email box down under the personal section of Mail. They can always be opened as long as Mail is installed. With Mail, as with other email apps, you can certainly close and reopen accounts. No problem. Creating the new account as you suggest may fix the problem. Or you might first go into Mail and then open Preferences and carefully check your account and password information. That is likely where the problem is.

Mac's Mail App is not as modern as iOS's Mail app, Many eMail providers now require a separate App Password different from your eMail password…

Using app passwords with apps that don't support two-step verification (microsoft.com)