imip inbound pop3 + mail w/o icalender attachment spams organizer

[dphi]

If there's an incoming mail that triggers:
[txdav.caldav.datastore.scheduling.imip.inbound#warn] Mail gateway didn't find an icalendar attachment in message
[txdav.caldav.datastore.scheduling.imip.inbound#warn] Mail gateway forwarding reply back to organizer

and pop3 is used, then

• this mail is forwarded every $polling_interval to the organizer, and
• the mail keeps sitting in that inbox

Suggested solution: Make

ccs-calendarserver/txdav/caldav/datastore/scheduling/imip/inbound.py

Line 190 in b736fd0

def shouldDeleteAllMail(serverHostName, inboundServer, username):

a configuration setting.