Hi,

 

Post SM 15.6 latest build, again seeing below such as frequently in error log which was not the earlier case

[2017.06.10] Application Error
[2017.06.10] =======
[2017.06.10] [CurrentUser: user12@abc.com]
[2017.06.10] [6/10/2017 5:36:13 AM]
[2017.06.10] https://secure.xyzhosting.com/Main/frmMessage.aspx?mode=preview&folder=Inbox&messageid=248673&mapped=False&user=user12&fromSearch=False&rowNumber=0&markUnread=false
[2017.06.10] 
[2017.06.10] System.Exception: Null exception (likely a 404 or something else produced by IIS)