Microsoft's own apps handle multiple accounts well: new Outlook for Windows, Outlook for Mac and the Outlook mobile apps all let you add several Outlook.com and Microsoft 365 accounts and switch between them. Outlook on the web is built around one signed-in account at a time, although work users can open shared mailboxes from it without a second sign-in. If you prefer the web version of Outlook and want a personal and a work account open side by side, use separate browser profiles or WebCatalog Desktop.
Add several accounts in the Outlook apps
If you already use Outlook's desktop or mobile app, this is the simplest option. Each account keeps its own mail, calendar and folders inside one app.
- New Outlook for Windows: go to View > View settings (or File > Account info), open Accounts > Your accounts, and select Add Account under Email accounts. Microsoft's guide to adding an email account to Outlook for Windows also covers classic Outlook and choosing a primary account.
- Outlook for Mac: open the Outlook menu > Settings > Accounts, click +, then Add an account, as described in Add an email account to Outlook for Mac.
- Outlook for iOS and Android: open Settings in the app, choose your account settings and tap Add Account (iOS steps, Android steps).
One thing has changed on the web: Microsoft removed connected accounts from Outlook.com, so outlook.com in a browser can no longer pull in Gmail or other outside accounts. Microsoft now points people to the Outlook desktop and mobile apps, or to forwarding, instead.
Open shared mailboxes in Outlook on the web
A team inbox such as support@ or a manager's delegated mailbox doesn't need its own sign-in. Once your Microsoft 365 admin has given you access, select your name in Outlook on the web, choose Open another mailbox, and enter the mailbox address. It opens in a separate browser window. Microsoft explains the details in Open and use a shared mailbox in Outlook on the web.
Two separate accounts in a browser
For two different Microsoft accounts, such as a personal Outlook.com address and a Microsoft 365 work account, the reliable browser setup is one browser profile per account. Each profile has its own cookies, so both accounts stay signed in, but they share your browser with everything else you have open.
Keep each Outlook account in its own window with WebCatalog Desktop
WebCatalog Desktop (macOS, Windows, and Linux) turns Outlook on the web into a desktop app with its own window and Dock or taskbar icon. Its profiles keep cookies and sessions separate, so your personal, work and client accounts can all stay signed in at once.
- Install WebCatalog Desktop and add Outlook from the catalog.
- Open Profiles and select Add profile. Name it, for example Work, and customize it if you like.
- Open Outlook with that profile and sign in with your work account. Microsoft's and your organization's sign-in rules, such as multifactor authentication or single sign-on, still apply.
- Repeat for your other accounts, for example Personal and Client A.
The help article on creating and managing profiles covers the details.
A profile isn't tied to one app. A Work profile can also hold Microsoft Teams, OneDrive and SharePoint signed in with the same Microsoft 365 account, while a Personal profile holds your Outlook.com account and personal OneDrive. You can then group each set in spaces, which open in their own window. Spaces only organize apps; the profiles are what keep the logins apart.
The app runs Outlook's web version, so each account stays in its own window. If you want every account in one combined inbox, new Outlook for Windows or Outlook for Mac is the better tool.
Conclusion
If you live in Outlook's desktop or mobile apps, add your accounts there. If you prefer Outlook on the web and want each account signed in and open in its own window, download WebCatalog Desktop.
