Accepted Domains is a comma delimited set of domains or partial domains that SiX is allowed to communicate with.  An asterisk (*) is not required to designate a wildcard as SiX will check if the domain or partial domain contains a value in the list.  This helps lock down the agent from sending and receiving events on certain domains.  By default, SiX can communicate with the following:
service-now.com
localhost
force.com
salesforce.com