Fix Outlook Error 0x80040201 (Sending Failed)

Outlook error 0x80040201 means your email program could not send a message, usually because of a problem with your outgoing mail server (SMTP) settings or a temporary network issue. The fix is to verify your SMTP server name and port, re-enter your password, and check that your account is not set to use an incorrect authentication method.

What Causes Error 0x80040201?

This error appears when Outlook tries to hand your message to the outgoing mail server and the server rejects the connection or the login. The most common triggers are:

• Wrong SMTP server address (for example, using the incoming POP/IMAP server name instead).
• Incorrect port number (25, 465, 587, or 2525) for your provider.
• Missing or incorrect “My outgoing server (SMTP) requires authentication” checkbox.
• An outdated or mistyped password, especially after a recent password change.
• Antivirus or firewall software blocking Outlook’s connection to the SMTP port.
• A temporary outage at your email provider’s SMTP server.

Fix 1: Check Your SMTP Settings

Most of the time, the error is a simple settings mistake. Here’s how to check them in classic Outlook for Windows:

1. Go to File > Account Settings > Account Settings.
2. Select your email account and click Change.
3. Click More Settings > Outgoing Server tab.
4. Tick “My outgoing server (SMTP) requires authentication” and choose “Use same settings as my incoming mail server” (unless your provider says otherwise).
5. Go to the Advanced tab. Check the outgoing server (SMTP) port number. Common ports: 587 (STARTTLS), 465 (SSL/TLS), or 25 (often blocked by ISPs).
6. Check the “Use the following type of encrypted connection” dropdown – it must match your provider’s requirement (usually TLS or SSL).
7. Click OK, then Next, and test by sending a message.

If you don’t know your provider’s exact SMTP settings, look them up on the provider’s official support page. Don’t guess – using the wrong port or encryption is the single most common cause of this error.

Fix 2: Re-enter Your Password

If your settings are correct but you still get 0x80040201, Outlook may have stored an old password. To force it to ask again:

1. Open Control Panel > Credential Manager (Windows).
2. Click Windows Credentials.
3. Look for entries under “Generic Credentials” that start with Microsoft.Office15 or Outlook and contain your email address.
4. Remove those entries.
5. Restart Outlook. It will prompt for your password – enter the current one.

If you use two-factor authentication, you may need an app-specific password from your provider. Regular account passwords often don’t work with SMTP when 2FA is enabled.

Fix 3: Disable Antivirus Email Scanning

Some security suites intercept SMTP traffic and can cause error 0x80040201. Temporarily disable the email scanning feature in your antivirus (not the whole protection) and try sending again. If that fixes it, re-enable the feature and instead add an exception for Outlook or for the SMTP port.

Also check Windows Firewall: make sure Outlook is allowed through. Go to Windows Security > Firewall & network protection > Allow an app through firewall and confirm Outlook is ticked for both Private and Public networks.

Fix 4: Create a New Outlook Profile

A corrupted profile can cause mysterious send failures. To rule it out, create a new profile and add your account again:

1. Open Control Panel > Mail (or search “Mail” in Windows).
2. Click Show Profiles > Add.
3. Give it a name like “NewProfile” and enter your email account details.
4. Set Outlook to always use this new profile (under “Always use this profile”).
5. Restart Outlook and test sending.

If the new profile works, your old profile was the problem. You can delete it later after confirming everything is fine.

Fix 5: Check for Outlook Add-ins

Occasionally, a third-party add-in interferes with sending. Start Outlook in safe mode by holding Ctrl while clicking the Outlook icon. If the error disappears, disable add-ins one by one:

1. Go to File > Options > Add-ins.
2. At the bottom, select “COM Add-ins” and click Go.
3. Uncheck all add-ins, restart Outlook normally, and test.
4. Re-enable them one at a time to find the culprit.

Fix 6: Repair Your Office Installation

If none of the above works, a damaged Office installation may be the cause. Run the built-in repair tool:

1. Open Settings > Apps > Installed apps (Windows 11) or Apps & features (Windows 10).
2. Find Microsoft 365 or Office in the list, click the three-dot menu, and choose Modify.
3. Select Quick Repair first. If that doesn’t help, try Online Repair (requires internet and takes longer).

Frequently Asked Questions

Why does error 0x80040201 happen only when sending, not receiving?

Because receiving (POP/IMAP) and sending (SMTP) use different servers and ports. Your incoming settings can be perfectly fine while the outgoing server address, port, or authentication is wrong. This error is specifically an SMTP failure.

Can I fix 0x80040201 by switching from SMTP to IMAP?

No. IMAP is for receiving mail. Sending always uses SMTP. Switching your account type won’t change the SMTP settings that cause this error.

Does this error happen in Outlook for Mac?

Yes, but the fix is similar. On Mac, go to Outlook > Preferences > Accounts, select your account, and check the outgoing server settings under “Server Settings”. The same SMTP port and authentication rules apply.

Will changing my SMTP port to 465 fix the error?

Only if your email provider actually supports 465 with SSL. If you force a port your provider doesn’t use, you’ll get the same error. Check your provider’s documentation for the correct port and encryption.

I use Gmail with Outlook and get this error. What should I do?

For Gmail, you need an app password if you have 2-Step Verification enabled. Also make sure the SMTP server is smtp.gmail.com, port 587 with TLS (or 465 with SSL), and “Requires authentication” is ticked. Google blocks less secure apps, so an app password is usually required.

Is error 0x80040201 the same as 0x8004210b?

No. 0x8004210b is a timeout error, while 0x80040201 is a general SMTP send failure. The causes can overlap (server unreachable), but the troubleshooting steps differ – timeout often points to firewall or network issues, while 0x80040201 is more often a settings or authentication problem.

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