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Outlook SMTP settings and test

Outlook.com and Hotmail send through smtp-mail.outlook.com, Microsoft 365 through smtp.office365.com, both on port 587 with STARTTLS. Test your login below.

Outlook.com / Hotmail

SMTP serversmtp-mail.outlook.com
Port587
SecuritySTARTTLS
UsernameYour full Outlook.com / Hotmail address
AuthenticationOAuth2, or an app password

Microsoft 365

SMTP serversmtp.office365.com
Port587
SecuritySTARTTLS
UsernameYour full Microsoft 365 address
AuthenticationOAuth2 (basic auth being retired)

Test Outlook SMTP

Outlook.com is pre-selected; switch the provider to Microsoft 365 for a work account. The test signs in with a username and password, so it shows whether your account still accepts password login over SMTP.

Your password is used for this one test and never stored or logged. We send one fixed test message; you can't change its content.

What this checks

  1. 1. Connect to server
  2. 2. Secure connection (TLS)
  3. 3. Log in
  4. 4. Send test email

If a step fails you get the server's exact reply and what it usually means.

Password login, app passwords and OAuth2

Microsoft is moving SMTP from passwords to OAuth2. Microsoft's own help page says Outlook.com requires Modern Auth (OAuth2), and Exchange Online is turning off basic authentication for SMTP client submission on Microsoft 365, with the dates pushed back more than once. In practice:

  • Outlook.com / Hotmail: many apps still connect with an app password. If yours is rejected, use an app that supports OAuth2 sign-in.
  • Microsoft 365: SMTP AUTH must be allowed for the mailbox, and the tenant must still accept basic auth. If you see 550 5.7.30, it no longer does, and the app needs OAuth2, Microsoft Graph or a sending service.

Turn on SMTP AUTH for a Microsoft 365 mailbox

  1. In the Microsoft 365 admin center, open Users → Active users and select the user.
  2. Open Mail → Manage email apps.
  3. Check Authenticated SMTP and save. It can take an hour to apply.

If the whole tenant has SMTP AUTH turned off, the per-mailbox setting has no effect until an admin allows it at the organization level.

Common Outlook SMTP errors

  • 535 5.7.139 Authentication unsuccessful: SMTP AUTH is off for the mailbox or tenant, or the password was rejected.
  • 550 5.7.30 Basic authentication is not supported: the tenant only accepts OAuth2 now.
  • 554 5.2.0 SendAsDenied: the From address isn't your mailbox or an alias you're allowed to send as.
  • Connection times out on port 465: Outlook doesn't accept 465. Use 587 with STARTTLS. See SSL vs STARTTLS.

FAQ

What is the Outlook SMTP server?
For Outlook.com, Hotmail and Live accounts it is smtp-mail.outlook.com. For work or school accounts on Microsoft 365 it is smtp.office365.com. Both use port 587 with STARTTLS.
Does Outlook SMTP still work with a password?
Microsoft says Outlook.com requires OAuth2 (Modern Auth), and is retiring password login (basic auth) for SMTP on Microsoft 365. Many apps still connect to Outlook.com with an app password. If the server answers "basic authentication is disabled", you need an app that signs in with OAuth2.
How do I create an app password for Outlook.com?
Turn on two-step verification in your Microsoft account security settings, then choose Create a new app password under App passwords. Use it in place of your normal password.
What does "535 5.7.139 Authentication unsuccessful" mean?
Microsoft rejected the login. On Microsoft 365 it usually means SMTP AUTH is turned off for the mailbox or the tenant, or the account needs multi-factor sign-in that SMTP can’t do. An admin can enable Authenticated SMTP for the mailbox in the Microsoft 365 admin center.
What does "550 5.7.30 Basic authentication is not supported for Client Submission" mean?
The Microsoft 365 tenant no longer accepts a username and password over SMTP. Switch the app to OAuth2, or send through Microsoft Graph or a sending service.
Can I use port 465 with Outlook?
No. Outlook.com and Microsoft 365 accept client submission on port 587 with STARTTLS. Port 465 is not supported.