Finding your SMTP server Outlook settings can solve delivery issues and help you configure email clients quickly. Whether you use the Outlook app, Outlook on the web, or desktop versions, the right server details keep your messages flowing reliably.
Follow this guide to locate the correct SMTP server for Outlook in different scenarios and avoid common authentication or connection errors.
| Service Type | SMTP Server Address | Port | Encryption |
|---|---|---|---|
| Outlook.com / Live.com | smtp.office365.com | 587 | STARTTLS |
| Microsoft 365 / Exchange Online | smtp.office365.com | 587 | STARTTLS |
| Legacy Outlook.com (old accounts) | smtp.live.com | 587 | STARTTLS |
| Authentication requirement | Your full Outlook email | Same as account password | Recommended |
Confirming Your Outlook Account Type
Before you check SMTP settings, determine whether your address ends with @outlook.com, @live.com, or is part of Microsoft 365 with a business domain. The server for most current Outlook accounts is smtp.office365.com, while older Live accounts may still use smtp.live.com.
Logging into webmail first helps you verify which service you are on and see the exact email address format. If your organization uses Microsoft 365 or Exchange Online, contact your IT admin for the preferred SMTP host, as policies may require using the corporate server instead of the public smtp.office365.com endpoint.
Understanding your account type ensures you select the correct port and authentication method, which reduces failures when you send large attachments or enable less common clients.
Finding SMTP Settings in the Outlook Desktop App
In the Outlook desktop application, you typically do not need to enter SMTP details manually because the program auto-configures them. However, if you set up the account manually or need to verify the values, open File, choose Account Settings, and then inspect the server entries listed for your email account.
For advanced troubleshooting, export or note the current settings, compare them with the official Outlook SMTP server standards, and update them only if prompted by your email administrator or when migrating to a new network.
Keep Outlook updated to ensure compatibility with the latest authentication requirements, especially when ports change or older protocols get deprecated by Microsoft.
Accessing SMTP Options in Outlook on the Web
Outlook on the web does not expose SMTP configuration to users, because Microsoft manages mail submission through its servers. To confirm which SMTP server Outlook uses when another client sends on your behalf, check your account details in the profile section and note the suggested server name.
If you connect external apps to Outlook.com or Microsoft 365, use smtp.office365.com with OAuth2 or app passwords as required, and avoid entering plain legacy passwords if your organization enforces modern authentication.
When in doubt, refer to the official Microsoft documentation for the most current settings, because policies around port 25, authentication, and encryption can change without notice.
Configuring Third-Party Email Clients
Popular clients like Thunderbird, Apple Mail, and Gmail allow manual entry of the SMTP server for Outlook. Use smtp.office365.com for current accounts, select port 587, and always enable STARTTLS or SSL depending on the client options.
Enter your full Outlook email as the username, and rely on modern authentication flows rather than basic legacy methods. Test the connection after setup by sending a small message before scheduling bulk emails.
Document the settings in a secure place and periodically verify them against Microsoft updates, especially if you rotate credentials or enable multi-factor authentication, which often requires app-specific passwords or OAuth.
Troubleshooting Common Connection Issues
If you encounter errors while sending, first verify that the port matches the encryption type, ensure that your firewall is not blocking outbound connections on port 587, and confirm that the SMTP server Outlook uses is still smtp.office365.com rather than an outdated address.
Authentication failures often stem from incorrect passwords, missing app-specific tokens, or disabled legacy protocols. Double-check account security settings and turn on Allow less secure apps only if your admin explicitly permits it for specific scenarios.
For persistent problems, review the logs in your email client, run Microsoft connectivity diagnostics, and reach out to support with the exact error codes to speed up resolution.
Best Practices for Managing Outlook SMTP Settings
- Always use smtp.office365.com for current Outlook.com and Microsoft 365 accounts.
- Prefer port 587 with STARTTLS over older ports to maintain compatibility and security.
- Keep your email client and operating system up to date to support the latest authentication standards.
- Use app-specific passwords or OAuth2 when multi-factor authentication is enabled.
- Document your SMTP configuration and periodically verify it against official Microsoft resources.
FAQ
Reader questions
How do I check which SMTP server my Outlook desktop client is currently using?
Open File, go to Account Settings, select the email account, and view the server information listed. If you see smtp.office365.com, that is the standard SMTP server for Outlook.
Can I use port 25 for the Outlook SMTP server, and what are the risks?
Port 25 is often blocked by residential ISPs and may not support modern authentication. Use port 587 with STARTTLS for reliable and secure delivery instead.
Will enabling two-factor authentication break my existing SMTP client for Outlook?
It can, because basic password authentication may be rejected. Generate an app-specific password or configure OAuth2 in your client to restore access without compromising security.
What should I do if I get an authentication error when switching to a new device?
Re-enter your full Outlook email and password or app-specific token, verify that the SMTP port and encryption match the recommended settings, and test again.