HP-UX Mailing Services Administrator's Guide

Sendmail 8.13.3
New Features in Sendmail 8.13.3
Chapter 3118
The following sections discuss the anti-spamming features in detail.
Message Quarantining
Starting with Sendmail 8.13.3, you can quarantine mail messages, which
are otherwise known as envelopes. Queue files or envelopes are stored
but not considered for delivery or display unless the “quarantine” state of
the envelope is undone, or delivery or display of the quarantined items is
requested.
Quarantined messages are tagged using the name hf for the queue file
instead of the name qf for the queue file, and by adding the quarantine
reason to the queue file.
When you run the following command, the quarantine reason is
displayed in a new line prefixed with QUARANTINE:
mailq -qQ
where, the -qQ option specifies the quarantined queue items.
Quarantined messages are not run on normal queue displays. They run
unless specifically requested with the -qQ option.
You can run and display restricted mail queues based on the quarantined
reason using the -qQtext option if the quarantine reason contains the
given text. Similarly, the -q!Qtext runs or displays quarantined items
which do not have the given text in the quarantine reason.
You can use the -qQ flag option to request the delivery or display of
quarantined items. Additionally, you can quarantine or unquarantine
messages already in the queue using the new -Q flag to Sendmail. For
example, the following command quarantines the normal queue items
matching the criteria specified by the -q[!][I|R|S|G][matchstring]
option using the reason given in the -Q flag:
sendmail -Qreason -q[!][I|R|S|G][matchstring]
Similarly, you can use the following command to change the quarantine
reason for the quarantined items matching the criteria specified by the
-q[!][I|R|S|Q][matchstring] option using the reason given on the -Q
flag:
sendmail -qQ -Q[reason] -q[!][I|R|S|Q|G][matchstring]
If you do not specify a reason, unquarantine the matching items and
make them normal queue items. The -qQ flag informs Sendmail to
operate on quarantined items instead of normal items.