Use either the :over or :under match-type tags to specify a numeric comparison. Both tags take a number as an argument to determine whether a test is "true" or "false". For example, the :over tag can compare a message's spam probability to determine if a particular message should be delivered.
if pmx_spam_prob :over 50 { pmx_quarantine; stop; }
In this example, the :over match-type is used to perform a numeric comparison. The :over match-type takes a number argument. The test is "true" if the message has a spam probability of over 50%.
if size :over 100K { pmx_file; discard; }
This example tests to see if the total message size is over 100K. If the message is over 100K, a copy of the message is filed in the quarantine. The message is then discarded.