Hello Klaus,
that warning means that your feature key for IronPort Antispam is going to expire in about two months. If you do not extend it by purchasing a new key, mailflow will continue as usual. However, the antispam engine will not do any scanning or updating after that date, means all spam not blocked by reputation filtering will pass trough.
In general, any key that expires will disable the associated service (antispam, antivirus, encryption, etc)., however, as the receiving key is always perpetual (exept on evaluation appliances), mailflow (receiving, HAT, RAT, Filters, Routes, Delivery) will continue as usual.
Hope that helps,
Andreas
