22.214.171.124. Specifying a Local Lockfile
Lockfiles are very useful with Procmail to ensure that more than one process does not try to alter a message simultaneously. Specify a local lockfile by placing a colon (
:) after any flags on a recipe's first line. This creates a local lockfile based on the destination file name plus whatever has been set in the
LOCKEXTglobal environment variable.
Alternatively, specify the name of the local lockfile to be used with this recipe after the colon.