Truly Understanding the Inbound Unsolicited Threshold
What is parameter INBOUND_UNSOLICITED_THRESHOLD?
There may be some misconceptions and misinterpretations wrt. the Workflow mailer parameter INBOUND_UNSOLICITED_THRESHOLD.
First, note that the WF documentation such as the WF Administrator's Guide or WF Developer's Guide makes no mention of such threshold because it is not configurable from the front end.
Second, the examples in the documentation are not meant to be read literally! For instance, in the WF Administrator's Guide, the reason it mentions raising of the event oracle.apps.wf.mailer.unsolicited on the "second" unsolicited E-mail is not because it is supposed to raise the event for every unsolicited E-mail but because the default threshold (INBOUND_UNSOLICITED_THRESHOLD) is 2. Notice too the documentation does not mention "second, third, fourth, etc." because that is not the intention of that parameter. Thus, the documentation is correct in reflecting what the code should do by default. And if INBOUND_UNSOLICITED_THRESHOLD is changed (obviously from the back end) to a value other than 2, then the documentation would seem broken.
The reason INBOUND_UNSOLICITED_THRESHOLD has a value of 2 is just to bring into attention that there are one too many unsolicited E-mails coming from a particular E-mail address because the mailer would only send one E-mail warning and would not be sending warnings forever.
1st unsolicited E-mail -> warning E-mail
2nd unsolicited E-mail -> raise event
other unsolicited E-mails -> ignored
What about parameter INBOUND_MAX_RET_EMAIL_SIZE?
There may also be some misconceptions and misinterpretations that parameter INBOUND_MAX_RET_EMAIL_SIZE is somehow tied to the parameter INBOUND_UNSOLICITED_THRESHOLD. That is not so. Parameter INBOUND_MAX_RET_EMAIL_SIZE is a maximum list size of unsolicited E-mail addresses and it is for a circular list. It has nothing to do with triggering events for unsolicited E-mails. Using it for any purpose other than what it was intended is a hack and should be avoided.