The connection to the outgoing (SMTP) server was dropped. Please check the outgoing (SMTP) server settings and try again.

Thanks for sharing the details, golfer1tx! Try to delete the stored credentials causing SMTP authentication drops

Outlook often keeps an old password/token in Windows Credential Manager. This causes SMTP to drop the connection before Outlook can send.

How to fix:

Open Control Panel

Go to Credential Managers

Click Windows Credentials

Find any entries for:

• smtp.*
• your email domain
• Outlook, MicrosoftOffice, or your email address

Remove every entry related to your email account

Restart Outlook

Outlook will prompt for your password → re-enter it

This alone fixes SMTP dropping in many cases when Outlook refuses to open the settings window.

See if this helps. If you need further assistance just let me know.

Best regards,

Kimberly

The SSO_POP_user… entry being re-created automatically means Outlook is authenticating via Modern Auth / SSO token, not basic SMTP credentials. Try to force Outlook to stop using SSO for SMTP.

Steps (Registry change – safe and reversible):

Close Outlook

Press Win + R → type regedit

Go to:

HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Common\Identity

Right-click → New → DWORD (32-bit) Value

Name it:

DisableADALatopWAMOverride

Set the value to 1

Close registry editor, restart windows and open outlook and try sending again.

Looks like another suggestion was sent to me, but when I click on the link, all I get is "404 - Page not found" This was after I advised that the last suggestion did not work. Thanks.