Okay, sorry to dismiss the earlier Server Fault message--it led me on the right track, at least. I called Dell support and had them walk me through disabling the performance features on the NIC, which resolved the issue. I think the key was disabling global chimney and receive side scaling, as I had tried most of the other steps as per the other Server Fault question posted. Of course none of these settings should cause problems, so maybe it's going to vary from server to server.
I also upgraded the driver version for the NIC, applied a BIOS patch and the latest Windows optional update rollup for Hyper-V issues, including a blue screen issue that we had experienced twice in the last week: KB2264080.
Here's the Dell support script I followed:
In a command prompt:
a. netsh int tcp set global chimney=disabled
b. netsh interface tcp set global rss=disabled
b. On each NIC inside the Broadcom Advanced Control Suite (BACS)
i. Disable IPv4 Checksum Offload
ii. Disable IPv4 Large Send Offload (LSO)
iii. Disable Receive Side Scaling (RSS)
. Uncheck the TCP Offload Engine (TOE) checkbox
v. Click Apply
Intel Configuration
a. Open Device Manager
b. On each Intel NIC in Device Manager, disable the following:
c. NOTE: Not every option is available or exist on the Advanced Tab.
i. Offload Receive IP Checksum
ii. Offload Receive TCP Checksum
iii. Offload TCP Segmentation
iv. Offload Transmit IP Checksum
v. Offload Transmit TCP Checksum
vi. IPV4 Checksum Offload
vii. Large Send Offload v2 (IPV4)
viii. Large Send Offload v2 (IPV6)
ix. Receive-Side Scaling
x. TCP Checksum Offload (IPV4)
xi. TCP Checksum Offload (IPV6)
In Windows Server 2008
1. Start à Run à CMD
2. netsh interface tcp set global rss=disabled
a. netsh int tcp set global autotuninglevel=disable
Best Answer
In EMC go to Recipient Configuration>Mailbox, find the mailbox for the departed user, right click and select properties, go to the Mail Flow Settings tab, select Delivery Options and click the Properties button. From there you can set the forwarding options.