Start with the right service
Outlook can mean the Outlook application or an Outlook.com mailbox. First identify both the application and the company hosting the address. A Gmail account used inside Outlook still needs Google’s authorization, not Outlook.com server settings.
Configuration quick reference
| Reference | What to check |
|---|---|
| Connection and access | For Outlook.com: IMAP outlook.office365.com, port 993, SSL/TLS; SMTP smtp-mail.outlook.com, port 587, STARTTLS; OAuth2 required. These are not universal settings for every account in Outlook. |
| Account authority | Use the original provider for identity verification, account recovery, eligibility and billing. |
Official reference: Microsoft Outlook.com settings. Check the provider’s current instructions before changing settings. Reviewed October 14, 2026.
Work through the problem
- Check whether the error occurs in Outlook on the web, new Outlook, classic Outlook or the mobile app.
- Test the mailbox at its provider’s official website before changing the Outlook profile.
- For Outlook.com mail in another client, use Modern Authentication/OAuth2. A client that only supports old basic authentication may not connect.
- If this is a work or school account, ask the organization’s administrator about access restrictions and service health.
Keep a useful diagnostic record
Note the exact error, the application and version, and whether the same account works on the provider’s website. Record whether sending, receiving or sign-in fails. Remove private message content from screenshots before sharing them.
If you use POP or local folders, preserve those messages before removing an account. A new account configuration may not recover data stored only on the old device.
Choose your next step
For an app-only problem, compare authorization and settings with the official reference above. For an account restriction or failed identity check, continue with the original provider. Independent assistance cannot bypass these controls.
Related guides: IMAP, POP and SMTP · Password recovery · Email synchronization.