Consider a Queue Extraction Service rule with a rule condition like Channel.QueueSizeBytes >= 102400, and a reset condition like Channel.QueueSizeBytes < 102400.

An alert will fire when a channel has a size >= 102400 bytes. Now suppose all the messages on that channel are deleted or expire. It would be hoped that the alert would be auto-acknowledged. However, in the cases of MSExchange2003 and MSExchange2007, that will not happen. In those MTAs, Channels are transient - they disappear soon after the messages have been processed. Hence (unless the extraction program happens to poll just before the channel disappears - which does sometimes happen but cannot be guaranteed) there will be no corresponding reset event.

Fortunately, Infonet and MSwitch queue extraction does not suffer from this problem as the channels are not transient.

However, all flavours of queue extraction are affected by a similar problem with rules using Originator fields; once a message has been processed it disappears, hence a reset event is not raised.

For now, it is not proposed to provide a fix: no customer has complained.

A possible fix would probably involve a SQL Server Agent Job that periodically auto-acknowledges old alerts. For example, if an old alert had been raised on a Channel which was not listed in a more recent poll of the Exchange2007Q Extraction Program, it could be assumed that the alert condition no longer applied.