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Outlook Receiving but Not Sending Emails: 6 Proven Fixes That Work

Jonathan Dough

Few things are more frustrating than discovering that Microsoft Outlook is receiving emails perfectly—but refusing to send them. For professionals and businesses that rely on seamless communication, this issue can cause delays, missed opportunities, and unnecessary stress. Fortunately, the problem is usually tied to a handful of common causes, most of which can be resolved quickly with the right approach.

TL;DR: When Outlook receives but does not send emails, the issue is usually caused by incorrect SMTP settings, authentication errors, a corrupted Outlook profile, oversized attachments, antivirus interference, or a damaged data file. Checking outgoing server settings and verifying credentials solve the problem most often. Restarting Outlook in safe mode or repairing the data file can also restore normal functionality. With the right troubleshooting steps, most sending errors can be fixed in under 30 minutes.

Below are six proven fixes that work, along with practical guidance on how to apply them.

1. Check Outgoing (SMTP) Server Settings

The most common reason Outlook cannot send emails—while still receiving them—is incorrect Simple Mail Transfer Protocol (SMTP) settings. Receiving emails uses incoming servers (IMAP or POP3), while sending requires SMTP. If SMTP settings are wrong or incomplete, outgoing emails will fail.

Users should verify the following:

To check these settings:

  1. Go to File > Account Settings > Account Settings.
  2. Select the affected email account.
  3. Click Change and then More Settings.
  4. Open the Outgoing Server tab.

Ensure that “My outgoing server (SMTP) requires authentication” is checked and that it uses the same login credentials as the incoming server.

This fix alone resolves a large percentage of sending failures.

2. Verify Username and Password

Incorrect login credentials can prevent Outlook from sending emails—even if it appears to be receiving them. Sometimes, incoming mail continues to work temporarily due to cached credentials, while outgoing mail fails immediately.

Common scenarios include:

Users should log directly into their email provider’s webmail portal to confirm that their password works. If two-factor authentication is enabled, an app-specific password may need to be generated and entered into Outlook.

After updating credentials in Outlook:

  1. Restart Outlook.
  2. Try sending a test message.

If the problem persists, continue with the next fix.

3. Disable Antivirus Email Scanning Temporarily

Antivirus software can sometimes block outgoing emails—especially if it detects large attachments or scans outgoing SMTP traffic.

Overprotective security settings may:

To test whether antivirus software is the culprit:

  1. Temporarily disable email scanning (not full protection).
  2. Send a test email.

If sending works, the solution may involve:

Important: Users should re-enable protection immediately after testing.

4. Check Attachment Size Limits

Oversized attachments can silently block outgoing mail. Many providers impose strict sending limits, typically between 20MB and 35MB.

Even if the message appears to send, it may remain stuck in the Outbox if it exceeds size limits.

Signs this is the issue:

Solutions include:

After reducing attachment size, the user should delete the stuck message, restart Outlook, and resend it.

5. Repair the Outlook Data File (PST or OST)

Corrupted Outlook data files can disrupt sending functionality while leaving incoming mail unaffected.

Outlook uses two primary file types:

If these files become corrupted due to improper shutdown, power outages, or disk issues, sending errors may occur.

Microsoft provides a built-in repair tool called ScanPST.exe.

Steps to repair:

  1. Close Outlook.
  2. Locate ScanPST.exe (usually in the Office installation folder).
  3. Run the tool and browse for the PST file.
  4. Click Repair.

For OST files, deleting the file and restarting Outlook may trigger automatic recreation and synchronization from the mail server.

This fix is particularly effective when Outlook crashes frequently in addition to sending issues.

6. Create a New Outlook Profile

When all else fails, creating a new Outlook profile often resolves sending problems caused by deep configuration errors.

Profiles store account settings, preferences, and configuration data. Corruption or conflicts within the profile can prevent SMTP from functioning properly.

To create a new profile:

  1. Close Outlook.
  2. Go to Control Panel > Mail.
  3. Select Show Profiles.
  4. Click Add to create a new profile.
  5. Set the new profile as default.

After setup, test sending a message. If successful, the issue was profile-related.

This method resolves stubborn issues that do not respond to simpler fixes.

Additional Troubleshooting Tips

If the six primary fixes do not solve the issue, users may also consider:

Safe Mode can be launched by pressing Windows + R and typing outlook.exe /safe.

Why Outlook Can Receive but Not Send

Understanding why this happens helps prevent recurrence. Outlook separates incoming and outgoing communication into two distinct processes:

This separation means one side may function normally while the other experiences authentication, port, or encryption errors. Because SMTP typically requires stricter authentication, it fails more frequently.

By focusing troubleshooting on outgoing server configuration first, users can save significant time.

Conclusion

When Outlook receives but refuses to send emails, the issue is rarely catastrophic. In most cases, it stems from incorrect SMTP settings, authentication problems, oversized attachments, antivirus interference, corrupted data files, or profile conflicts. Methodically applying the six proven fixes outlined above resolves the vast majority of cases.

Rather than reinstalling Outlook immediately, users should start with SMTP verification and credential checks, then move toward data repair and profile recreation if necessary. With systematic troubleshooting, email functionality can typically be restored quickly and efficiently.

Frequently Asked Questions (FAQ)

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