+PH/01 If a system filter or a router generates more than SHRT_MAX (32767)
+ child addresses, Exim now panics and dies. Previously, because the count
+ is held in a short int, deliveries were likely to be lost. As such a
+ large number of recipients for a single message is ridiculous
+ (performance will be very, very poor), I have chosen to impose a limit
+ rather than extend the field.
+