Connect on Android OS

Go into Settings then Accounts (sometimes called Accounts and backup and then Manage accounts)
Select Add account and pick Corporate, ActiveSync, or Exchange (The naming depends on your specific Android device or if you using the built-in Andriod email client or a 3rd party client like Gmail).
For email address, enter your full username@earlham.edu address (Some phones will try to set it up automatically and fail so if you see a Setup manually you should select that)
Enter the password for your Earlham account
The Domain\Username isn't used by Zimbra but some clients require the username in place (without the @earlham.edu)
For Server, enter: zimbra.earlham.edu
For Port use 443
For Security, type check to use SSL/TLS or "Use secure connection (SSL).
Select Done