Adding an Additional Mailbox in Outlook 2013 is very similar to the process for Outlook 2007 and Outlook 2010. Here’s a quick guide borrowed from groovypost.

Open Outlook 2013 and Click File.

Add Mailbox Outlook 2013 - Click File

Click Info, Account Settings, Account Settings…

Add Mailbox Outlook 2013 - Click Info Account Settings

Highlight your current email account and click Change

Add Mailbox Outlook 2013 - Click Change

Server settings box should appear, click More Settings.

Add Mailbox Outlook 2013 - Click More Settings

Click the Advanced Tab and Click Add

Add Mailbox Outlook 2013 - Click Advanced, Add

Type in the name of the additional / second mailbox you want to add and click OK. In my example I’m adding a shared mailbox we use for RFP responses.

Add Mailbox Outlook 2013 - Type Mailbox Name Click OK

Confirm the new mailbox was resolved by the server and Click OK to save.

Add Mailbox Outlook 2013 - Click OK to Save

Here we are back on the Server Settings screen. Click Next.

Add Mailbox Outlook 2013 - Click Next

Click Finish

Add Mailbox Outlook 2013 - Click Finish

Click Close on the Accounts Settings page.

Add Mailbox Outlook 2013 - Click Close

Your new additional mailbox should be listed under your main account or PST files if you have already added to your account.

Add Mailbox Outlook 2013 - New Additional Mailbox Listed