When using Microsoft Outlook, the correct SMTP and IMAP settings are important for sending, receiving, and synchronizing email. A wrong server name, port, encryption method, or authentication setting can prevent Outlook from connecting to the mailbox.
This guide explains how SMTP and IMAP work, the common server settings used by popular email services, how to configure an account in New Outlook and Classic Outlook, and how to troubleshoot common connection problems.
Outlook SMTP and IMAP settings at a glance
If you need the server details first, use the table below. For a custom-domain or hosted mailbox, confirm the values with the email provider or administrator before entering them in Outlook.
| Email service | IMAP settings | SMTP settings | Authentication |
|---|---|---|---|
| Outlook.com / Hotmail / Live | outlook.office365.comPort: 993 SSL/TLS |
smtp-mail.outlook.comPort: 587 STARTTLS |
OAuth2 / Modern Authentication. IMAP access may need to be enabled in Outlook.com settings. |
| Microsoft 365 / Exchange Online | outlook.office365.comPort: 993 SSL/TLS |
smtp.office365.comPort: 587 STARTTLS |
Modern Authentication is preferred. In Outlook, normally add the mailbox as Microsoft 365/Exchange instead of manually forcing IMAP. |
| Gmail / Google Workspace | imap.gmail.comPort: 993 SSL/TLS |
smtp.gmail.com587 with STARTTLS or 465 with SSL/TLS |
Use Google’s secure sign-in flow when available. App passwords apply only to supported scenarios. |
| Custom-domain email | Provider-specific | Provider-specific | Use the settings supplied by the hosting provider or mail administrator. |
Why SMTP and IMAP are important in Outlook
SMTP and IMAP handle different parts of email communication:
- IMAP (Internet Message Access Protocol) lets Outlook access and synchronize mailbox folders and message state with the mail server.
- SMTP (Simple Mail Transfer Protocol) submits outgoing email to the mail server for delivery.
| Feature | IMAP | SMTP |
|---|---|---|
| Purpose | Accesses and synchronizes mailbox data | Sends outgoing messages |
| Common secure port | 993 with SSL/TLS | Provider-specific; 587 with STARTTLS is common |
| Mailbox synchronization | Synchronizes folders and message state | Does not synchronize mailbox folders |
| Storage | The mail server stores the mailbox; IMAP provides synchronized access | SMTP transfers outgoing mail and is not a mailbox storage protocol |
Prerequisites before setting up Outlook
Before configuring an account, make sure you have:
- The current version of Outlook supported by your environment.
- Your full email address.
- The correct IMAP server name, port, and encryption method.
- The correct SMTP server name, port, and encryption method.
- The authentication method required by the provider.
- Permission to use IMAP or SMTP if your organization controls access to these protocols.
- A stable network connection.
Do not assume that an email address and password are always enough. Outlook.com and Microsoft 365 use Modern Authentication/OAuth in supported scenarios, and other providers may also require secure provider sign-in or an app password for specific legacy applications.
How to add an account in New Outlook for Windows
New Outlook normally attempts to detect the correct account settings automatically. Use automatic setup whenever the provider is supported.
- Open New Outlook.
- Select Add account at the bottom of the folder list, or open Settings and choose Add account under Accounts.
- Enter the email address and select Continue.
- Complete the provider’s sign-in and authorization steps.
- If Outlook requests manual server information for the account, enter the exact IMAP and SMTP settings supplied by the provider.
- After the account is added, send a test message and confirm that incoming messages synchronize correctly.
How to configure IMAP and SMTP in Classic Outlook
Use Classic Outlook’s advanced setup when you need to enter the incoming and outgoing server information manually.
- Open Classic Outlook and select File > Add Account.
- Enter the email address.
- Select Advanced options, enable Let me set up my account manually, and select Connect.
- Select IMAP.
- Enter the incoming IMAP server, port, and encryption settings supplied by your provider.
- Enter the outgoing SMTP server, port, and encryption settings supplied by your provider.
- Enter the required credentials or complete the provider’s secure sign-in process.
- Select Connect and allow Outlook to validate the account.
- Send and receive a test message after setup.
How to update existing SMTP and IMAP settings in Classic Outlook
You may need to change the settings after a server migration, password change, provider update, or connection problem.
- Open Outlook and select File.
- Select the required account under Account Information.
- Select Account Settings.
- Choose Server Settings.
- Review the incoming mail server, port, username, and encryption settings.
- Review the outgoing mail server, port, authentication, and encryption settings.
- Select Next and then Done after Outlook validates the changes.
Troubleshooting SMTP and IMAP issues in Outlook
| Problem | Possible cause | What to check |
|---|---|---|
| Outlook keeps asking for a password | Authentication or authorization problem | Reauthenticate the account. Check whether OAuth, Modern Authentication, or a provider-supported app password is required. |
| Can receive but cannot send | SMTP configuration | Verify the SMTP server, port, encryption, and outgoing authentication. |
| Can send but cannot receive | IMAP configuration | Verify the IMAP server, port, SSL/TLS, and whether IMAP access is enabled. |
| Authentication failed | Legacy authentication is blocked | Use the provider’s current OAuth or Modern Authentication method. |
| Gmail does not connect | Google authorization or account policy | Use the Google sign-in flow and confirm that the account is allowed to connect to Outlook. |
| Microsoft 365 manual IMAP setup fails | Protocol or administrator policy | Add the mailbox as Microsoft 365/Exchange when possible. Ask the administrator whether IMAP is enabled if it is specifically required. |
Check firewall, VPN, and security restrictions
A firewall, VPN, proxy, endpoint-security product, or corporate network rule can block a mail connection. Do not disable antivirus or firewall protection as a normal troubleshooting step. Instead, verify whether Outlook and the required ports are allowed, or ask the administrator to review the restriction.
If the server details are correct but Outlook still cannot connect, see how to fix Outlook not connecting to the server for additional account, profile, network, and Outlook data-file checks.
IMAP vs POP: which should you use?
IMAP is generally the better choice when you access the same mailbox from multiple devices because it keeps folders and message state synchronized with the server.
POP mainly downloads messages to the email client and is better suited to specific legacy or single-device workflows. If mailbox synchronization across Outlook, mobile devices, and webmail is important, IMAP is usually the more appropriate option.
When IMAP migration is more appropriate than manual Outlook setup
Manual SMTP and IMAP settings are useful when you need to configure a single mailbox in Outlook. For an organization that needs to move several mailboxes between email platforms, configuring each mailbox manually is time-consuming and does not provide a structured migration workflow.
EdbMails IMAP Migration Tool provides a dedicated interface to connect the source IMAP server, select the required destination, map mailboxes, and run the migration. Depending on the selected operation, EdbMails supports IMAP to Office 365, IMAP to Live Exchange, IMAP to IMAP, IMAP to Outlook PST, and Outlook PST to IMAP.
The EdbMails workflow separates Source Connection, Target Connection, and Mailbox Mapping, allowing administrators to configure and review each stage before starting the migration. The application can also process multiple mailboxes in parallel, which is more practical than adding and transferring mailboxes one at a time through Outlook.
Before starting an IMAP migration, verify the source server hostname, port, authentication requirements, and provider-side IMAP access. Correct source connection details help avoid authentication and connectivity errors during migration.
When should you use EdbMails IMAP Migration?
Use manual Outlook configuration when you only need to add an individual mailbox to Outlook. Use EdbMails IMAP Migration when the requirement is to move mailbox data between IMAP-supported email systems or to supported Microsoft destinations through a managed migration workflow.
What if an Outlook OST file becomes inaccessible?
An SMTP or IMAP connection error does not automatically mean that the Outlook data file needs to be converted. If the original mailbox and Outlook profile are still available, first correct the account configuration, reconnect the mailbox, and allow Outlook to synchronize again.
If the original mailbox is unavailable and only an orphaned or inaccessible OST file remains, Outlook does not provide a normal method to import that OST into another profile. In such cases, recoverable mailbox data can be exported to PST using an EdbMails OST to PST Converter. Recovery depends on the condition and readable data available in the source OST file.
Best practices for SMTP and IMAP settings in Outlook
- Use server names and ports published by the email provider.
- Use SSL/TLS or STARTTLS according to the provider’s instructions.
- Use OAuth or Modern Authentication when required.
- Keep Outlook updated for current authentication and security support.
- Test both sending and receiving after changing account settings.
- Do not disable security software as a routine troubleshooting method.
- For Microsoft 365 mailboxes in Outlook, prefer Microsoft 365/Exchange account setup over manual IMAP.
- For multiple mailbox transfers, use a migration workflow rather than manually reconfiguring every mailbox.
Frequently asked questions
What are the IMAP settings for Outlook.com?
Use outlook.office365.com as the IMAP server, port 993, SSL/TLS encryption, and OAuth2 or Modern Authentication. Outlook.com IMAP access may need to be enabled under Settings > Mail > Forwarding and IMAP.
What are the SMTP settings for Outlook.com?
Use smtp-mail.outlook.com as the SMTP server, port 587, STARTTLS encryption, and OAuth2 or Modern Authentication.
Should I use SMTP port 465 or 587 in Outlook?
Use the port specified by your email provider. Port 587 with STARTTLS is commonly used for authenticated SMTP submission. Some providers also support port 465 with SSL/TLS, but 465 is not a universal alternative for every mail service.
Why can Outlook receive email but not send it?
Check the SMTP server name, port, encryption method, and outgoing authentication. Also verify that your email provider or administrator permits SMTP access for the account.
Why does Outlook keep asking for my password?
Repeated password prompts can occur when credentials are outdated, the provider requires OAuth or Modern Authentication, an app password is required for a supported legacy scenario, or the account needs to be authorized again.
Should I use IMAP or POP in Outlook?
IMAP is generally better when the same mailbox is used on multiple devices because it synchronizes folders and message state with the server. POP is mainly suited to workflows that intentionally download mail to a device.
Should Microsoft 365 accounts be configured manually as IMAP in Outlook?
Usually no. Add a Microsoft 365 work or school mailbox as a Microsoft 365 or Exchange account and allow Outlook to configure it automatically. Use IMAP only when a specific application requires it and the administrator has enabled IMAP access.
What if an old Outlook OST file is inaccessible?
If the original mailbox and profile are still available, first repair or reconnect the account and allow Outlook to synchronize. If only an orphaned or inaccessible OST remains, recoverable data may need to be exported to PST using an OST recovery or conversion solution.
Conclusion
Correct Outlook configuration starts with the settings supplied by the service that hosts the mailbox. Verify the IMAP and SMTP server names, ports, encryption method, and authentication requirements before changing the account.
Use automatic account setup whenever Outlook supports the provider, especially for Outlook.com and Microsoft 365 accounts. Use manual IMAP configuration only when it is required. If the requirement involves moving several mailboxes rather than configuring one Outlook profile, an IMAP migration process is more appropriate.
