All GroupWise users on Windows Server no longer able to connect or receive mail affecting GroupWise Windows, Webaccess and IMAP clients

  • 7024887
  • 27-Oct-2020
  • 24-Nov-2020


GroupWise 18
GroupWise 2014
Windows Server


A recent update to Malwarebytes anti-malware software running on Windows Server causes performance and connection issues for GroupWise agents as of October 2020, that can affect the GroupWise Windows, Webaccess and general IMAP clients.


Disable the Malwarebytes service from starting and running on the GroupWise server.


The anti-malware software now attempting to quarantine the GroupWise agents, confusing them for harmful services.

Additional Information

Symptoms noted:
1.  The GroupWise Windows client could not login to the mailbox.

2.  The GroupWise Webaccess client sometimes took about 10 minutes of waiting to login to the mailbox.

3.  Those already logged into their GroupWise mailboxes did not have any mail flow in or out of the Post Office.

4.  General IMAP clients did not have any mail sync.

5.  The user activity as noted in the Post Office Agent log seemd normal, no signes of latency.

6.  Once the "Malwarebytes" windows service was shutdown and disabled, then the problems noted in this document all went away.