dos filetimes (S)
Under DOS and Windows, if a user can write to a file they can
change the timestamp on it. Under POSIX semantics, only the owner
of the file or root may change the timestamp. By default, Samba
runs with POSIX semantics and refuses to change the timestamp on a
file if the user smbd is acting on behalf of is not the file owner.
Setting this option to
yes allows DOS semantics and smbd(8) will change the file
timestamp as DOS requires. Due to changes in Microsoft Office 2000
and beyond, the default for this parameter has been changed from
"no" to "yes" in Samba 3.0.14 and above. Microsoft Excel will
display dialog box warnings about the file being changed by another
user if this parameter is not set to "yes" and files are being
shared between users.
Default: dos filetimes = yes