The current find criteria only allows exact matching on the subject line. Even though variables may be used, it does not allow other assertion types that you would normally get with mabl tests (such as contains, starts with).
My use case: the application under tests sends multiple messages after configuring it with the mabl mailbox. Sometimes the order of delivery of the messages is not deterministic. Sometimes there is a race condition between the test execution and the application sending notifications. It would be so much easier to create a find criteria that :
if subject is not this pattern, or
if subject starts with this pattern