You fail to receive the email from quarantine digest and after running manually the command you receive this message:
# pmx-qdigest --verbose
pmx-qdigest: scanning messages starting from 2013-04-23 00:06:25
pmx-qdigest: scanned 0 messages.
...the date returned is ahead of the current date.
First seen in
PureMessage for Unix 6.0
What To Do
Run pmx-qdigest with --earliest switch to re-run the job.