Adding a mailbox in Outlook means connecting a second email account so you can read and send from both places without switching between programs

Outlook lets you add multiple email accounts to the same window. When you add a mailbox, Outlook downloads messages from that account and displays them alongside your primary inbox. You can switch between accounts, reply from either one, and manage them all from a single interface. This is different from forwarding — the original account stays active, and you're simply viewing it through Outlook.

The steps differ slightly depending on whether you're using Outlook on Windows, Mac, or the web version. The core process is the same: you tell Outlook the email address and password, it verifies the account with the email provider, and then your messages appear in a separate folder within Outlook.

Key Takeaways

  • Adding a mailbox requires the email address and password for the account you want to connect, plus permission from that account's provider if it uses two-factor authentication.
  • Outlook on Windows and Mac use slightly different menu paths, but both require you to go to account settings and select the option to add a new account.
  • If Outlook cannot connect, the most common cause is an incorrect password or a security setting that blocks third-party apps from accessing the account.
  • Once added, each mailbox appears as a separate folder in your Outlook sidebar, and you can choose which account to send from when composing a message.

Adding a mailbox in Outlook on Windows

Open Outlook and go to File in the top menu. Select Info, then click Add Account. A dialog box will open asking for the email address of the account you want to add. Type the full email address and click Next.

Outlook will attempt to detect your email provider automatically. If it recognizes the provider (Gmail, Yahoo, Outlook.com, and most corporate accounts), it will ask for your password. Enter it and click Next. Outlook will verify the connection. If successful, the account is added and you'll see a confirmation message.

If Outlook cannot detect your provider, it will ask you to choose the account type manually. Most personal email accounts use IMAP or POP3. IMAP is usually the better choice because it keeps your messages synced across devices. You'll need to enter the incoming and outgoing mail server addresses for your email provider — these are available on the provider's website or in your account settings.

Adding a mailbox in Outlook on Mac

Click Outlook in the top menu and select Preferences. In the Preferences window, click Accounts. At the bottom of the accounts list, click the + button to add a new account.

A dialog will open. Select your email provider from the list if it appears, or choose Other Email Account if your provider is not listed. Enter your email address and password, then click Continue. Outlook will verify the connection. Once confirmed, the account appears in your accounts list and messages will begin downloading.

Adding a mailbox in Outlook on the web

Log into Outlook.com or your organization's Outlook web portal. Click the gear icon in the top right corner and select View all Outlook settings. Go to Mail and then Accounts. Click Connected accounts (or Add account depending on your version).

Enter the email address and password for the account you want to add. Click Next and wait for Outlook to verify the connection. Once verified, messages from that account will appear in a folder labeled with the account name in your sidebar.

What to do if Outlook cannot connect to the mailbox

The most common reason Outlook fails to connect is an incorrect password. Double-check that you've entered the password correctly — passwords are case-sensitive. If you're unsure, reset the password through the email provider's website and try again.

Some email providers, including Gmail and Yahoo, require you to generate a separate password for third-party apps like Outlook. This is a security feature. If you're adding Gmail, you'll need to create an App Password through your Google Account settings rather than using your regular Gmail password. For Yahoo, you may need to generate an App Password in your Yahoo Account Security settings. Check your email provider's support page for the exact steps.

If you have two-factor authentication enabled on the account, you may need to approve the connection on your phone or through a security code before Outlook can access it. Some providers will send you a notification asking you to confirm that Outlook is trying to connect — approve it and try adding the account again.

If the problem persists, try removing the account and adding it again. In Windows, go to File > Info > Account Settings > Account Settings, select the account, and click Remove. On Mac, go to Outlook > Preferences > Accounts, select the account, and click the − button. Then add it again from the beginning.

Managing multiple mailboxes in Outlook

Once you've added a mailbox, it appears in your folder list on the left side of Outlook. Each account has its own inbox, sent items, and other folders. You can click on any inbox to view messages from that account.

When you compose a new message, look for the From field. Click it to choose which account to send from. By default, Outlook uses your primary account, but you can change this for any message. If you want to reply to a message from a specific account, Outlook automatically sets the From field to that account.

You can also create rules to organize messages from different accounts. In Windows, go to File > Info > Manage Rules & Alerts. On Mac, go to Outlook > Preferences > Rules. Rules let you automatically move messages to folders, flag them, or perform other actions based on the sender or account.

Removing a mailbox from Outlook

If you no longer want to access an account through Outlook, you can remove it without affecting the original account. The email will still exist on the provider's servers — you're only disconnecting Outlook from viewing it.

In Windows, go to File > Info > 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. Confirm the removal when prompted.

Frequently Asked Questions

Can I add a work email and a personal email to the same Outlook window?

Yes. Outlook supports multiple accounts regardless of provider or type. You can add a Gmail account, a work email, an Outlook.com account, and others all to the same Outlook window. Each appears as a separate folder in your sidebar.

Will adding a mailbox to Outlook delete messages from the original account?

No. Adding a mailbox to Outlook only lets you view the account through Outlook. The messages remain on the email provider's servers. If you remove the account from Outlook later, the messages are still there.

What's the difference between adding a mailbox and forwarding?

Forwarding sends copies of new messages from one account to another, but the original account becomes inactive in your inbox. Adding a mailbox keeps both accounts active and lets you read and send from either one without forwarding. You control which account to send from for each message.

Why does Outlook ask for a password instead of letting me log in with my phone?

Outlook needs a password or app-specific password to access your account in the background. It cannot use the phone-based login that works in a web browser. If your provider requires two-factor authentication, generate an app password through your account settings and use that instead of your regular password.

Can I add the same email account twice to Outlook?

Outlook will not let you add the same account twice. If you try, it will show an error saying the account is already connected. If you need to access the account under different settings, remove it first and add it again with the new configuration.