Adding a mailbox to Outlook means connecting a second email account to the same program
Outlook lets you add multiple email accounts — work, personal, family — to one inbox view. When you add a mailbox, you're telling Outlook to fetch and display messages from that account alongside your primary one. You don't have to switch between programs or log out and back in. Everything arrives in the same place.
The steps differ slightly depending on whether you're using Outlook on the web (outlook.com), Outlook on your desktop computer, or Outlook on your phone. The core idea is the same: you provide Outlook with the email address and password for the account you want to add, and Outlook handles the rest.
Key Takeaways
- You can add up to 10 email accounts to Outlook on the web, and the process takes about five minutes per account.
- Outlook stores passwords in encrypted form, but you should use a strong, unique password for each email account you add.
- When you add a mailbox, you choose whether to see all accounts in one inbox or keep them separate — this affects how you spot scams across accounts.
- Some email providers (like Gmail) require you to create an app-specific password before Outlook can connect, rather than using your regular login password.
- If Outlook can't connect to a mailbox, the most common reason is that two-factor authentication is turned on and you haven't created an app password yet.
How to add a mailbox in Outlook on the web
Go to outlook.com and sign in to your primary account. In the top right corner, click the gear icon (Settings), then select "View all Outlook settings." Click "Mail" in the left sidebar, then "Accounts" near the top. You'll see a button that says "Add account" — click it.
Type in the email address of the account you want to add. Outlook will ask for the password. Enter it and click "Next." If the account uses two-factor authentication (a code sent to your phone or generated by an app), Outlook will prompt you for that code. Once you've entered it, click "Add this account." Outlook will verify the connection, which usually takes a few seconds.
After the account is added, you'll see it listed under "Accounts." You can now choose how you want to view it: in a combined inbox with your primary account, or in a separate folder. If you want to keep them separate, click the account name and toggle "Show in combined inbox" off.
How to add a mailbox in Outlook on your computer
Open Outlook and go to File (top left), then "Add Account." Type in the email address of the account you want to add and click "Connect." Outlook will open a window asking for your password. Enter it and click "Next."
If the account uses two-factor authentication, you'll be asked to verify your identity — usually by entering a code sent to your phone. Once verified, Outlook will test the connection and add the account to your sidebar on the left. You'll see the new mailbox listed under your primary account.
To change how the account appears in your inbox, right-click the account name in the sidebar and select "Properties." You can rename it, change the folder structure, or adjust notification settings for that specific account.
What to do if Gmail or Yahoo won't connect
Gmail and Yahoo have stricter security rules than Outlook. They don't allow Outlook to connect using your regular password, even if it's correct. Instead, you need to create an app-specific password — a separate, temporary password that only Outlook can use.
For Gmail: Go to myaccount.google.com, click "Security" on the left, scroll down to "App passwords," and select "Mail" and "Windows Computer" (or whatever device you're using). Google will generate a 16-character password. Copy it, go back to Outlook, and paste it when asked for the password instead of your regular Gmail password.
For Yahoo: Go to account.yahoo.com, click "Account security" on the left, then "Generate app password." Select "Other App," type "Outlook," and click "Generate." Yahoo will create a password. Copy it and use it in Outlook instead of your regular Yahoo password.
If you don't see "App passwords" in Gmail or Yahoo, it means two-factor authentication isn't turned on for that account. Turn it on first, then create the app password.
How to organize multiple mailboxes so you can spot scams across accounts
When you have multiple accounts in Outlook, scammers sometimes send similar phishing emails to all of them at once, or to different accounts over time. Keeping them organized helps you notice the pattern.
If you turned on "Show in combined inbox," all messages from all accounts appear together, sorted by date. This makes it easier to spot if the same suspicious email arrived in multiple accounts. You can also create a rule that flags emails from unknown senders across all accounts — go to Settings, then "Mail," then "Rules," and click "Add new rule."
If you keep accounts separate, check each one regularly for similar suspicious messages. Look for the same sender address, the same urgent language, or requests for the same type of information (passwords, account numbers, verification codes). If you see the same scam in multiple accounts, report it to each email provider and delete it from all accounts.
Security considerations when adding multiple mailboxes
Each email account you add to Outlook should have its own strong, unique password. If one account is compromised, a strong unique password means the attacker can't use it to break into your other accounts. A strong password is at least 12 characters long and includes uppercase letters, lowercase letters, numbers, and symbols.
Outlook stores passwords in encrypted form on your device, which means they're scrambled and unreadable to anyone who isn't you. However, if someone gains access to your computer or phone, they could potentially access all your mailboxes without needing the passwords. Protect your device with a PIN or password, and don't leave it unattended in public.
If you're adding a work email account, check with your IT department first. Some organizations don't allow their email to be added to personal email clients like Outlook, or they require you to use a special setup process. Adding it without permission could violate your company's security policy.
Removing a mailbox from Outlook if you no longer need it
In Outlook on the web, go to Settings, then "Mail," then "Accounts." Find the account you want to remove and click the trash icon next to it. Outlook will ask you to confirm. Click "Yes, remove this account." The account is removed from Outlook, but the actual email account still exists — you're just disconnecting it from this program.
In Outlook on your computer, right-click the account name in the left sidebar and select "Delete Account." Confirm the deletion. Again, this only removes it from Outlook; the email account itself is not deleted.
If you're removing an account because you think it's been hacked, change its password when ready after removing it from Outlook. Then check the account's recovery email and phone number to make sure they haven't been changed by an attacker.
Frequently Asked Questions
Can I add an email account that's not from Outlook, Gmail, or Yahoo?
Yes. Outlook supports most email providers, including corporate email systems, university accounts, and smaller providers. When you click "Add account," Outlook will try to detect the provider automatically. If it can't, you may need to enter the server address manually — your email provider's support page will have this information.
What happens to emails in the added account — are they copied to Outlook or just viewed?
Emails are viewed through Outlook, not copied to it. They stay on the original email server. If you delete an email in Outlook, it's deleted from the original account too. If you read an email in Outlook, it shows as read in the original account as well.
Can I send emails from the added mailbox, or only receive them?
You can send and receive from all added mailboxes. When you compose a new email, you'll see a "From" dropdown that lets you choose which account to send from. This is useful if you want to reply to work emails from your work account and personal emails from your personal account.
If I add an account to Outlook on my computer, will it also appear on my phone?
No. Each device is separate. If you want the same accounts on your phone, you'll need to add them to the Outlook app on your phone using the same steps. You can add them to some devices and not others — it's your choice.
What should I do if Outlook says "We couldn't connect to your account"?
The most common reason is that two-factor authentication is turned on and you haven't created an app-specific password. Check the account's security settings and create an app password if needed. If the account doesn't use two-factor authentication, double-check that you've typed the password correctly — passwords are case-sensitive. If you've forgotten the password, use the email provider's "Forgot password" link to reset it, then try adding the account again.