This article applies to:

• MailMarshal SEG
• MailMarshal SPE

Symptoms:

• Error message similar to:
  
  06032 15:39:06.765 Event - Failed to bind socket to <[0.0.0.0]:25>, an MTA (SMTP)-Simple Mail Transport Protocol server is probably already running (typically the Windows 'Simple Mail Transport Protocol' service) - 10048 - WSAEADDRINUSE
  
  Running netstat shows no other application using this port.

Causes:

• Microsoft Update KB4338815 has been installed.
• Note that this issue does not originate in SEG. SEG operation is affected by the operating system update.

Resolution:

• Uninstall the named Microsoft Windows Update
• Install a fix from Microsoft, such as KB4345424. Fixes refer to "TCP port in use" with SQL Server, but the same fix applies to other ports such as port 25.

Notes:

This article will be updated with any further information available.