If you need to manage multiple Gmail accounts, there are several ways to do it.
The simplest method One way is to log into each account in a different browser -- for example, you can log into your consumer Gmail in Google Chrome and your Lehigh Gmail in Firefox.
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In the example above, sek2@lehigh.edu is the primary account. The consumer Gmail account sek4278@gmail.com is a second login, while the LTS inlts@lehigh.edu account is a delegated account as the indicated by the (delegated) text. Delegated accounts appear automatically when you log into your primary account.
Another way is create separate profiles for different accounts within the browser. For instance in google chrome, on the right side of the address bar, you'll see a round circle with a letter for your username or your photo. You can click on that and add an additional profile which remains complete separate from the one you started with.
For more information view the Gmail Help page on multiple accounts.