are you using POP3 account
are you using the default mail application on the mac
you will need to know details etc
suggest they may be on the email site you regestered with about setting up accounts on oter mail applications.
In the default mail programme on mac called "Mail'
You are given Account type (CHANGE TO POP3)
Description (TYPE IN FULL EMAIL ADDRESS)
Email Address: (TYPE IN EMAIL ADDRESS AGAIN)
Full name (FULL NAME OF USER OF THE EMAIL ADDRESS)
Incoming Server: pop.towson.edu (mey be this but need to check with email provider)
user name: your logon username for mail
Password: your password for email
outgoing mail server: smtp.towson.edu (may be this again need to check with email provider on their site for info)