i made a website using domain and webhosting from yahoo....they gave me email addresses to...like [email protected]

i made couple of more email address for my co workers...not all of us use yahoo mail, therfore they were having trouble linking to this new email address....is there a way i can make a email portal that will be a part of my website...like www.mail.mysite.com or mysite.com/mail

does yahoo provide this service....like if my coworker gets on the website....he would click on 'Email' and a pop-wup will ask him to put in his email address and password and then he can check his business email for there directly...

thanks