If Exchange 2007 queue is growing fast and you want to find who is the top contributor, below code helps you. You need to run this code from a exchange management shell since the code involves Exchange cmdlets like get-message.
Find top 10 senders in Exchange Queue:
$senders = @{}
$queuemessages = Get-message -Resultsize unlimited
$queuemessages | % { $senders[$_.FromAddress] = $senders[$_.FromAddress] + 1 }
$senders.getenumerator() | sort value -last 10
Similarly you can filter the Get-Message output by recipients to get the top recipients.