Mac OS X Mail.app Authenticated SMTP Configuration
To start, go to the Mail menu, and select "Preferences." Click the
"Accounts" icon, and you should see the image below:

Click on "Add Account", and you should see the window below. If you are
editing an existing account, be sure to click "Edit" instead of "Add
Account." Click on "Outgoing Mail Server", and choose the "Add
Server..." option. This will add a new SMTP server to Mail.app.

Now you should see the "SMTP Server Options" window, like the one
below.

The outgoing mail server should be set to "smtp.cs.umd.edu". Leave the
server port as the default 25, and select the "User Secure Sockets
Layer (SSL)" option.
We only support Password authentication currently.
Password with SSL:
First contact staff and obtain a CS Kerberos5
password. Now, choose "Password" as the authentication method. Please
make sure that you have checked SSL, as outlined above. Otherwise this
will not work.
Enter your user name for "User Name", and your CS Kerberos5
password for the password.
Next, make sure that you have the newly created SMTP server selected:

Once it is selected, all further email from that account should be sent
through that "smtp.cs.umd.edu".