Files with mco file extension can be found as winks - animated emoticons for Microsoft Live Messenger.
Software that open mco file
MCO file extension - MSN Messenger wink
What is mco file? How to open mco files?
The mco file extension is mainly related to flash-based animated emoticons used in Microsoft Live. Used to spice up chats with little animations instead smileys.
These are also called winks.
This mco file type entry was marked as obsolete and no longer supported file format.
This type of file is no longer actively used and is most likely obsolete. This is typically the case for system files in old operating systems, file types from long discontinued software, or previous versions of certain file types (like documents, projects etc.) that were replaced in higher versions of their original programs.
The default software associated to open mco file:
Company or developer:
Microsoft Corporation
Windows Live Messenger also known as MSN Live Messenger is instant messaging application developed by Microsoft. Live Messenger supports text chat as well as audio and video callings. It was merged with Skype.
Windows Live Messenger for Mac 
Company or developer:
Microsoft Corporation
Windows Live Messenger for Mac allows users to communicate or collaborate on the fly, sharing instant messages, presence information, or files across time zones and locales. You can even make audio or video calls with contacts on the Mac or on Windows.
It was eventually merged with Skype, but previous versions are still available for download as part of Windows Essentials.
List of recommended software applications associated to the .mco file extension
Recommended software programs are sorted by OS platform (Windows, macOS, Linux, iOS, Android etc.)
and possible program actions that can be done with the file: like open mco file, edit mco file, convert mco file, view mco file, play mco file etc. (if exist software for corresponding action in File-Extensions.org's database).
Unspecified and all other actions for computer programs working with mco file - MSN Messenger wink
Click on the software link(s) for more information. Suggested software applications use mco file type for internal purposes and/or also by different way than common edit or open mco file actions.
