This is a Windows system installed file with Windows File Protection (WFP) enabled.
There are 56 versions of msoe.dll in the wild, the latest version being 6.00.3790.4657 (srv03_sp2_gdr.100129-1424). The average file size is about 1.25 MB. Some variations of the file have been seen to be installed with the program WSE_Astromenda from installCore.
(Note, the behaviors below are for all versions of msoe.dll, select a unique version for details.)
Marked as a safe ActiveX control for Internet Explorer (digitally signed with script execution permission)
United States installs about 28.28% of Outlook Express.