Outlook lets you add a second mailbox and keep your first inbox. Choose Add Account in the app's account settings, then sign in with the additional address. Desktop and mobile apps have different menus.
Outlook.com in a browser works differently: it no longer adds or syncs third-party connected accounts such as Gmail. To read that mail alongside your Outlook account, use an Outlook app. The website's old connected-account setting is gone.
In this guide
Check that you're adding an existing mailbox
Have the full email address ready and check how you normally sign in to it. Adding an account tells Outlook how to reach an existing mailbox; it doesn't create a new email address or combine two Microsoft accounts into one identity.
Use the provider's normal sign-in when Outlook opens it. A work mailbox may also need your organization's sign-in approval or device-management setup.
Keep the current Outlook account in place while adding the second one.
Microsoft says its Windows account setup instructions apply when adding more accounts as well as the first.
Choose the branch that matches the Outlook app on your screen.
For the opposite arrangement, our Outlook account in Gmail guide adds Microsoft mail to the Gmail phone app. That uses a different app's settings from the Outlook procedures here.
Open Your accounts in new Outlook
Open View > View settings. Another current route is File > Account info. In Settings, choose Accounts > Your accounts.
Under Email accounts, click Add Account. Choose a suggested account if it's the one you want, or type the other email address. Click Continue and complete the account's sign-in prompts.
Some providers, including Gmail, Yahoo, and iCloud, need additional account settings or permission approval before Outlook can connect.
Read the provider's prompt rather than repeatedly entering a password into the wrong account's sign-in page.
When setup finishes, return to Outlook's mail view and look for the newly added account. Open that account's inbox specifically and check for a message you recognize. The original account should still be available separately.
To make the new account primary, return to Accounts > Your accounts, select Manage beside it, and choose Set as primary account. Adding the mailbox doesn't automatically make it your primary account.
Use the classic Outlook account wizard
For the classic Windows app, choose File > Add Account. Type the additional address, click Connect, and follow the prompts. If asked, enter the account password again, then complete OK > Finish.
The existing inbox doesn't have to be removed first. These steps work whether you're adding your first mailbox or another one to the same Outlook app.
If those controls don't match your screen, check the app version before continuing. New Outlook uses its Accounts settings; classic Outlook uses the File-menu account wizard. Instructions for one won't always match the other.
An IMAP or iCloud account may need an app password, which is a special password your provider creates for an app. Use the provider's current account instructions when prompted, rather than turning off account security to get past setup.
Add another account on a Mac
In current Outlook for Mac, select Tools > Accounts and choose + Add Account at the bottom of the account list. Enter the second email address and follow the sign-in prompts, then choose Done.
If starting through the app's settings, use Outlook > Settings > Accounts > + Add Account. Both routes let you add the account, so use whichever your version offers.
Legacy Outlook for Mac uses Tools > Accounts, then the + control and Add an Account. Complete that address's setup and choose Done. The label differs from the current app's + Add Account button.
If your provider opens a sign-in or permissions page in the browser, finish those steps and allow it to return to Outlook when asked. After signing in through the browser, check that the mailbox appears back in Outlook.
The Mac setup steps distinguish current and legacy layouts.
Don't delete an already working account just because the newer screenshot has a differently labeled button.
Use the account controls on iPhone, iPad, or Android
On current Outlook for iOS, tap Inbox at the top of the app, then open Settings. Select Account > Add Account > Email Account, enter the address, and finish signing in.
On Outlook for Android, open the app menu, then Settings > Account > Add Account. Choose Add an email account, or Add Google Account for that offered route, and complete sign-in.
Choose Add Account for an address you already have. Create New Account starts a different task. If Outlook suggests an account automatically, check the address before accepting it.
Complete any multi-factor authentication request, such as an approval in your authenticator app. For a managed work account, follow the organization's required setup or ask its administrator which mobile-access requirements apply.
Confirm both receiving and the sender address
Open the added inbox and check its latest messages. Then compose a small test message to an address you can check, checking From before sending. Select the intended account if Outlook has chosen the other one.
I'd make that sender check before replying to work mail. Having both inboxes open is convenient, but it also makes choosing the wrong address easier when switching between personal and work messages.
For a mailbox that was added successfully and later starts failing, use the Outlook account-sync repair guide.
Adding yet another copy of the same mailbox can make the account list harder to understand.
If setup never finishes, record the exact error and whether it appears in Outlook or the provider's sign-in window. For work mail, give the administrator that error, device type, and Outlook version.
For personal mail, check sign-in with the provider before contacting Outlook support.
The Short Version
Use Accounts > Your accounts > Add Account in new Outlook, File > Add Account in classic Outlook, or Tools > Accounts on Mac. Mobile Outlook has its own Add Account controls.
Finish signing in with your provider, then check the inbox and sender address.
Checked November 11, 2026.
