SMTP Settings for Outlook: Find IMAP, POP3 and Outgoing Mail Server Details
Correct SMTP settings are required to send email from Outlook, mobile mail apps, websites, scanners, and business software. Incoming email normally uses IMAP or POP3, while outgoing email uses SMTP.
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What Is SMTP?
SMTP is used for outgoing message submission and transfer. If Outlook receives messages but cannot send them, the SMTP hostname, port, encryption, authentication, password, or provider policy may be wrong.
What Is IMAP?
IMAP synchronizes mail and folders across several devices. Reading, moving, and deleting messages normally updates the server.
- Common secure port: 993
- Encryption: SSL/TLS
- Username: usually the full email address
- Authentication: required
What Is POP3?
POP3 downloads messages to a client and may remove them from the server depending on settings.
- Common secure port: 995
- Encryption: SSL/TLS
- Best suited to specific single-device or local-archive workflows
IMAP vs POP3
| Feature | IMAP | POP3 |
|---|---|---|
| Multi-device synchronization | Yes | Limited |
| Server folders | Yes | Usually no |
| Modern default choice | Usually yes | Only for specific needs |
Common SMTP Ports
587
Widely used for authenticated submission with STARTTLS.
465
Widely used for SMTP submission over implicit TLS.
25
Mainly used for server-to-server transfer and often restricted for client submission.
Information Required for Outlook
- Email address
- Password or app password
- Incoming hostname
- IMAP or POP3 selection
- Incoming port and encryption
- SMTP hostname
- SMTP port and encryption
- SMTP authentication requirement
How to Configure Outlook
- Open account settings.
- Choose Add Account.
- Enter the full email address.
- Try automatic setup.
- Use advanced setup if detection fails.
- Choose IMAP or POP3.
- Enter incoming and outgoing settings.
- Enable SMTP authentication.
- Test sending and receiving.
Why Outlook Receives but Cannot Send
- Wrong SMTP hostname
- Wrong port
- Incorrect encryption type
- SMTP authentication disabled
- Username is not the full address
- Password or app password is wrong
- Firewall blocks the port
- Provider has restricted the account
- Outbound IP has a reputation problem
Repeated Password Prompts
Possible causes include an incorrect or expired password, MFA, an app-password requirement, disabled legacy authentication, a wrong username, or an account lockout.
SSL Certificate Warnings
A warning can appear when the configured hostname does not match the certificate, the certificate is expired, or local security software intercepts TLS.
Check the mail server certificate.
Email Setup Checklist
- Confirm the provider.
- Check MX records.
- Verify hostnames.
- Verify ports and encryption.
- Enable SMTP authentication.
- Check MFA or app-password requirements.
- Test ports.
- Inspect SSL.
- Review provider status and account restrictions.
Frequently Asked Questions
Should I use IMAP or POP3?
IMAP is usually better for users who access email from multiple devices.
Which SMTP port should I use?
Follow the provider's instructions. Port 587 with STARTTLS and port 465 with implicit TLS are common.
Why is port 25 blocked?
Many providers restrict client use of port 25 to reduce spam and abuse.
Do I need SMTP authentication?
Most modern providers require authenticated message submission.
Conclusion
Successful mail configuration depends on correct server names, ports, encryption, authentication, and account policy.
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