Xeams acts as an SMTP client when sending emails out. A connection time out occurs can occur due to network connjection. How many emails do you have in your Outbound Queue and do they eventually get sent out?

Off course rebooting the machine will most likely solve this issue but try doing netstat to see how many open TCP/IP connections you have. It is also possible that too many sockets have already been created on the machine. Netstat should tell you that.