exchange 2007: recipient limits
quick ways to check recipient limits
global setting:
Get-TransportConfig | fl
mailbox setting:
Get-Mailbox -Identity <mailbox> | fl
or
Get-Mailbox -Identity <mailbox> | fl RecipientLimits
additional info:
http://technet.microsoft.com/en-us/library/bb310760(v=exchg.80).aspx