For attaching files in Outlook, you need to use our WebDAV Drive Mapping service. You can map DriveHQ cloud storage as a network drive (like C:). WebDAV is included in our cloud IT service for free.
DriveHQ FileManager is our native client, so it has more features than WebDAV, e.g. it supports file sharing, publishing, folder synchronization, encrypted folder and many other features. It is designed to be more efficient and robust. If you need to upload / download large files or many files, it is recommended using FileManager, not only it is faster than a mapped drive, it is also faster than FTP.