Adding a mailbox to Outlook means connecting a second email account to the same program window

You can add another email account to Outlook without leaving the program or switching between windows. Outlook lets you manage multiple mailboxes in one place — whether they are Gmail, Yahoo, corporate email, or other Outlook accounts. The steps differ slightly depending on whether you are using Outlook on Windows, Mac, or the web version, but the basic process is the same: you enter the account details, Outlook connects to the mail server, and the new mailbox appears in your folder list.

Most people add a second mailbox because they have work and personal email, or they manage email for a business or family member. Once added, you can read, send, and organize mail from both accounts without opening a separate browser tab or program.

Key Takeaways

  • You can add a second mailbox by going to File > Add Account (Windows) or Outlook > Preferences > Accounts (Mac), then entering the email address and password.
  • Outlook automatically detects most email providers, but some accounts may require you to enter the mail server address manually.
  • Two-factor authentication on your email account may require you to use an app password instead of your regular password.
  • Once added, the new mailbox appears as a separate folder in your sidebar, and you can send mail from either account using the From field.

Adding a mailbox on Windows Outlook

Open Outlook and go to File in the top menu. Click Add Account. A window will open asking for your email address. Type the full email address of the account you want to add and click Next. Outlook will try to detect your email provider automatically.

If Outlook recognizes the provider, it will ask for your password. Enter it and click Next. If you use two-factor authentication on that email account, you may need to generate an app-specific password instead of using your regular login password — check the security settings of the email account you are adding. Once Outlook connects, click Finish, and the new mailbox will appear in your folder list on the left side of the screen.

If Outlook does not recognize the provider, it will ask for additional details like the incoming and outgoing mail server addresses. You can find these in the email provider's help section or by searching "[email provider] IMAP settings" online. Enter the server addresses, port numbers, and encryption type as listed, then click Next and Finish.

Adding a mailbox on Mac Outlook

Open Outlook and click Outlook in the top menu bar. Select Preferences. In the Preferences window, click Accounts. At the bottom left, click the + button to add a new account.

A dialog will appear asking you to choose the account type. Select Email Account. Enter your email address and click Continue. Outlook will attempt to detect your provider. If it succeeds, enter your password and click Add Account. If detection fails, you will need to enter the mail server details manually — the same information you would use on Windows.

Once the account is added, close the Preferences window. The new mailbox will appear in your folder list, and you can start reading and sending mail from it immediately.

Adding a mailbox in Outlook on the web

Go to outlook.com or outlook.office.com and sign in with your primary account. Click the Settings gear icon in the top right corner. Select View all Outlook settings. Click Mail in the left sidebar, then click Accounts.

Click Add another account. Enter the email address of the account you want to add and click Next. Enter the password and click Next. Outlook will verify the connection. Once confirmed, the account will appear in your account list, and you can switch between mailboxes using the account selector at the top of the page.

What to do if the password does not work

If Outlook rejects your password, the most common reason is two-factor authentication. Many email providers, including Gmail, Yahoo, and Microsoft accounts, require an app-specific password when you connect to third-party programs like Outlook. This is a security feature that prevents someone with your regular password from accessing your email through other apps.

To generate an app password, go to the security settings of the email account you are trying to add. Look for "App passwords" or "Less secure app access" depending on the provider. Generate a new password for Outlook, then use that password instead of your regular one when adding the account. If you are unsure where to find this setting, search "[email provider] app password" to find the exact steps.

Sending mail from a specific mailbox

Once you have added a second mailbox, you can send mail from either account. When you compose a new message, look for the From field at the top of the compose window. Click it to see a dropdown list of your email addresses. Select which account you want to send from, then write and send your message as usual.

If you do not see the From field, you may need to enable it. In Windows Outlook, go to File > Options > Mail and check the box next to "Always show From." On Mac, go to Outlook > Preferences > Composing and enable the From field there.

Organizing mail from multiple mailboxes

Each mailbox appears as a separate folder in your sidebar, with its own Inbox, Sent Items, Drafts, and other folders. You can create rules to automatically sort incoming mail into folders, or you can create a new folder that pulls messages from both accounts. This is useful if you want to see all mail from a specific person or project in one place, regardless of which account it came to.

To create a search folder in Windows Outlook, right-click Search Folders in your sidebar and select New Search Folder. Choose your search criteria and click OK. On Mac, go to File > New Smart Folder and set up your search the same way. You can also use the search bar at the top of Outlook to find messages across all your mailboxes at once.

Frequently Asked Questions

Can I add more than two mailboxes to Outlook?

Yes. Outlook does not limit the number of accounts you can add. You can add as many as you need, though managing many accounts in one window can become cluttered. Each mailbox appears as a separate folder in your sidebar.

Will adding a mailbox delete the original messages from that account?

No. Adding a mailbox to Outlook only reads your existing messages — it does not change anything on the email server. Your messages remain in the original account, and you can still access them from any other device or program you use to check that email.

What if I want to remove a mailbox from Outlook?

On Windows, go to File > Account Settings > Account Settings, select the account you want to remove, and click Remove. On Mac, go to Outlook > Preferences > Accounts, select the account, and click the − button. The mailbox will disappear from Outlook, but your messages will remain on the email server.

Can I set up automatic forwarding instead of adding a mailbox?

Yes, if you prefer. Most email providers let you set up forwarding rules so that mail sent to one account automatically goes to another. This happens on the email server itself, not in Outlook. Check your email provider's settings for forwarding options. This approach works if you want all mail in one inbox, but it does not let you send from both addresses.