Outgoing Mail not working on MacBook

outgoing email from my hotmail account not working, incoming is working fine. each time I get error saying, email not sent and rejected from the server. however I am able to send emails from my iPhone but just not from my MacBook Pro (Big Sur). it was working fine for years with no issues, but suddenly started this issue a week ago.

I am using the native MAIL app. tried reading other articles online with manual SMTP settings, but nothing works.

any suggestions would be appreciated.