I went to a site that just had a migration from 2003 SBS to 2011 SBS. The Exchange Server was setup normal. The 5 Clients was setup with 2 accounts one Pop Accounts and SMTP Account pointing to the ISP. THe second account pointing to the EXchange. The default delivery for both account is the Exchange Mailbox. The exchange server is getting all types of transport errors the transport service is constantly crashing. Event ID 7004 MSEXChange Transport, Event ID 10003 10001 Poison Message Source MSExchange Transport. For now my boss wants to keep the Outlook setups and MX records pointing towards first Pop accounts but wants me to resolve the transport issue. Any help would be greatly appreciated.