Q: Mail does not recognise my email password

My mail keeps asking me for the password for hotmail/outlook accounts and then cannot verify them. It also asks me to link to a server but refuses to send mail.

It happens on my macbook air and i-mac, but not the i-pad air.

I also have problems deleting old accounts and keep getting asked for the password.

How can I completely clean the mail app and renter the data with just what I want?