SMTP settings for Outlook
These are the SMTP settings you need to send email using an Outlook.com or Microsoft account through a third-party app, website, or email client.
This applies to:
- Outlook.com
- Hotmail.com
- Live.com
- Microsoft 365 / Exchange Online mailboxes
SMTP settings
| Setting | Value |
| SMTP server | smtp.office365.com |
| Port | 587 |
| Encryption | STARTTLS |
| Authentication | Required |
| Username | Your full Outlook email address |
| Password | Your account password or app password |
Notes:
- Outlook requires SMTP authentication.
- If your account uses multi-factor authentication, you may need to generate an app password.
- These settings apply to both personal Outlook accounts and Microsoft 365 accounts.
Before you start
Before using Outlook’s SMTP server, check the following:
- SMTP authentication is enabled for your account.
- You are using your full email address as the username.
- Multi-factor authentication is set up, if required.
- Your app or platform supports STARTTLS on port 587.
If SMTP authentication is disabled at the account or tenant level, emails will fail to send.
How to use these settings
- Open the email or SMTP settings in your app or platform.
- Select SMTP as the outgoing mail server.
- Enter smtp.office365.com as the server address.
- Set the port to 587 and enable STARTTLS.
- Turn on authentication.
- Enter your full Outlook email address and password or app password.
- Save the settings and send a test email.
Common SMTP issues and quick fixes
| Issue | Likely cause | Quick fix |
| Authentication failed | Password or app password is incorrect | Generate a new app password or re-enter your credentials |
| Connection timed out | Port 587 is blocked or TLS not supported | Allow port 587 and enable STARTTLS |
| Emails won’t send | SMTP authentication is disabled | Enable SMTP authentication for the mailbox |
| Access blocked by Microsoft | MFA enabled but app password missing | Create an app password and use it for SMTP |
Sending limits
Outlook and Microsoft 365 apply daily sending limits:
- Personal Outlook accounts: limits vary and are not publicly fixed.
- Microsoft 365 accounts: limits depend on your plan and tenant policies.
Limits reset on a rolling basis and include all SMTP-sent messages.
Conclusion
Using the correct Outlook SMTP settings helps avoid authentication errors, blocked connections, and failed sends. With SMTP authentication enabled and the right port and encryption in place, most issues come down to credentials or account-level restrictions.
For more context around email authentication and sending behaviour, these Warmup Inbox glossary articles are useful references:
- What is SPF? – Learn how SPF helps receiving servers trust your mail.
- What is DKIM (DomainKeys Identified Mail)? – Understand how DKIM adds a cryptographic signature to your messages.
- What is DMARC? – See how DMARC ties SPF and DKIM together for stronger email authentication.
- How to unsend an email – A quick explanation of recall and undo options in modern email clients.
