mlock 7:2002edebian1-13.2 (i386 binary) in ubuntu gutsy

 C-client is a library of functions for accessing mail folders and messages.
 It was written as part of the University of Washington IMAP server, but has
 since found other use as well.
 .
 libc-client.so uses this program to lock mailbox files so they don't get
 corrupted.