Outlook is not sending or receiving email: initial troubleshooting

What to check when Outlook stops sending or receiving emails?

First try the same account in Outlook on the web. If it works there, the problem is usually with the app, profile, sync, an add-on, or your computer. If it does not work on the web either, it is worth checking the license, quota, service status, rules, security and mailbox configuration.

Risks to review

• Delete profiles, OST or PST files before identifying what information exists only locally.
• Repeatedly forward messages and generate duplicates.
• Ignore rules, forwards or suspicious access to a compromised account.
• Use old clients that do not support modern authentication.

Safe recommendations

1. Try sending and receiving from Outlook on the web and from another trusted network.
2. Review the service status, mailbox quota, license, and messages in the outbox.
3. Use the Sync function and confirm whether the application shows disconnection or credentials request.
4. Update Outlook and temporarily disable add-ins only to isolate the problem.
5. Review rules, forwarding, devices, and recent activity if the behavior is unexpected.
6. Create a new profile only after protecting local files and documenting the current configuration.

When to seek specialized help

• The problem affects multiple users or the entire domain.
• There are missing messages, unknown forwards or suspicious logins.
• There is a large, damaged PST or with information that does not appear on the web.