After Migration to Exchange 2013 you have some errors in eventlog.
Event ID : 1019
Failed to start listening (Error: 10049). Binding: 10.100.1.10:143
SBS only supports 1 NIC at a time. Exchange was trying to communicate with both NIC’s thus it could not start listening on the 2nd one.
So basically this issue occurs if the IMAP service is not configured to listen on a local IP address or if the receive connectors for the Transport service cannot bind to an IP address.
The IMAP Service needs to bind itself to one of the local Adapters on the exchange server.
To resolve this issue, configure the IMAP service to listen on a local IP address, and configure the receive connector to listen on all IP addresses.
“netstat -a” will show you current listening ports bound to IP/interface.
This example sets the IP address and port for communicating with Exchange by using IMAP4 with no encryption or TLS encryption.