Fix Outlook SMTP Error 0x800c8101 When Using App Password

draft · accounts-and-access passwordauthenticationsmtp

Generated by docuprocessor (prompt article/v3) · 2026-04-22 14:37

Source thread

thread_id: spaces/AAAA05BdS6s/threads/HJw3Hehi4ik · 3 msgs · first 2024-12-31 · participants: Tech A

Tech A 2024-12-31 21:55

For pds, I'm having some troubles with the outgoing server (SMTP):

image/png image.png

**Microsoft Outlook – Internet Email Settings Dialog (Advanced Tab)** The Advanced tab displays IMAP incoming server port set to **993** with **SSL/TLS** encryption, and SMTP outgoing server port set to **465** with **SSL/TLS** encryption. Server Timeout is set to **1 minute** (slider positioned at Short end). The checkbox **"Purge items when switching folders while online"** is checked; **"Do not save copies of sent items"** and **"Mark items for deletion but do not move them automatically"** are both unchecked.

Tech A 2024-12-31 21:55

(no text)

image/png image.png

**Outlook Internet Email Settings dialog – Outgoing Server tab** is displayed. "My outgoing server (SMTP) requires authentication" is checked, with "Log on using" selected; User Name field shows **mdkabir@pdsmgmt.com**, Password field is masked (asterisks), and "Remember password" is checked. "Require Secure Password Authentication" is unchecked; the parent window shows a POP/IMAP Account Settings configuration screen with "Test Account Settings" panel visible in the background.

Tech A 2024-12-31 21:56

I'm using an app password

image/png image.png

The Microsoft Outlook "Add Account" / "Test Account Settings" dialog displays an error on the **Errors** tab: **"Send test email message: An unknown error occurred, error code: 0x800c8101."** The account being configured uses the username **mdkabir@pdsmgmt.com** with "Remember password" checked and "Require logon using Secure Password Authentication" unchecked. The Stop button is visible alongside a Close button, indicating the test sequence has completed or halted.

---
title: "Fix Outlook SMTP Error 0x800c8101 When Using App Password"
category: accounts-and-access
tags: ["password", "authentication", "smtp"]
source_thread_id: "spaces/AAAA05BdS6s/threads/HJw3Hehi4ik"
source_space: "spaces/AAAA05BdS6s"
generated_at: "2026-04-22T14:37:51"
participants: ["Tech A"]
---

# Fix Outlook SMTP Error 0x800c8101 When Using App Password

## Problem
Outlook test account settings fails with error code 0x800c8101 when attempting to send a test email message. The configuration uses SMTP port 465 with SSL/TLS encryption and an app password for authentication. The incoming IMAP settings (port 993 with SSL/TLS) appear correctly configured, but the outgoing server authentication fails during the test sequence.

## Resolution
This error typically occurs when using an app password with incorrect SMTP authentication settings. Verify the following configuration:

1. Ensure SMTP server requires authentication is checked
2. Select "Log on using" option (not "Use same settings as my incoming mail server")
3. Enter the complete email address in the User Name field
4. Use the app password (not the regular account password) in the Password field
5. Verify "Require Secure Password Authentication" is unchecked when using app passwords
6. Confirm SMTP port is set to 465 with SSL/TLS encryption
7. Test the account settings again

If the error persists, regenerate a new app password from the email provider and replace the existing password in the configuration.

## References
- Source discussion: `spaces/AAAA05BdS6s/threads/HJw3Hehi4ik`
- Attachments:
  - ![image.png](../attachments/HJw3Hehi4ik.4177QiOY_tk/image.png) — **Outlook Internet Email Settings dialog – Outgoing Server tab** is displayed. "My outgoing server (SMTP) requires authentication" is checked, with "Log on using" selected; User Name field shows **mdkabir@pdsmgmt.com**, Password field is masked (asterisks), and "Remember password" is checked. "Require Secure Password Authentication" is unchecked; the parent window shows a POP/IMAP Account Settings configuration screen with "Test Account Settings" panel visible in the background.
  - ![image.png](../attachments/HJw3Hehi4ik.HJw3Hehi4ik/image.png) — **Microsoft Outlook – Internet Email Settings Dialog (Advanced Tab)**

The Advanced tab displays IMAP incoming server port set to **993** with **SSL/TLS** encryption, and SMTP outgoing server port set to **465** with **SSL/TLS** encryption. Server Timeout is set to **1 minute** (slider positioned at Short end). The checkbox **"Purge items when switching folders while online"** is checked; **"Do not save copies of sent items"** and **"Mark items for deletion but do not move them automatically"** are both unchecked.
  - ![image.png](../attachments/HJw3Hehi4ik.cYVGDELn8po/image.png) — The Microsoft Outlook "Add Account" / "Test Account Settings" dialog displays an error on the **Errors** tab: **"Send test email message: An unknown error occurred, error code: 0x800c8101."** The account being configured uses the username **mdkabir@pdsmgmt.com** with "Remember password" checked and "Require logon using Secure Password Authentication" unchecked. The Stop button is visible alongside a Close button, indicating the test sequence has completed or halted.

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