Red Hat LINUX 7.2 Reference Manual page 277

Section 16.5:Procmail
To ensure that the action on this last previous matching recipe was successfully completed before
allowing a match on the current recipe, use the a flag instead.
• B — Parse the body of the message and look for matching conditions.
• b — Use the body in any resulting action, such as writing the message to a file or forwarding it.
This is the default behavior.
• c — Generate a carbon copy of the email. This is useful with delivering recipes, since the required
action can be performed on the message and a copy of the message can continue being processed
in the rc files.
• D — Makes the egrep comparison case-sensitive. By default, the comparison process is not
case-sensitive.
• E — Similar to the A flag, except that the conditions in this recipe are only compared to the
message if the immediately preceding recipe without an E flag did not match. This is comparable
to an else action.
Use the e flag instead if you only want this recipe checked if the preceding recipe matched but the
action failed.
• f — Uses the pipe as a filter.
• H — Parses the header of the message and looks for matching conditions. This occurs by default.
• h — Uses the header in a resulting action. This is the default behavior.
• w — Tells Procmail to wait for the specified filter or program to finish and report whether or not
it was successful before considering the message filtered.
If you would like to ignore "Program failure" messages when deciding whether a filter or action
succeeded, use the W option instead.
Additional flags can be found in the procmailrc man page.
Specifying a Local Lockfile
Lockfiles are very useful with Procmail to ensure that more than one process does not try to alter a
certain message at the same time. You can specify a local lockfile by placing a : character after any
flags on a recipe's first line. This will create a local lockfile based on the destination filename plus
whatever has been set in the LOCKEXT global environment variable.
Alternatively, you can specify the name of the local lockfile to be used with this recipe after the :
character.
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