Failover API can be queried using both JSON and XML. Bing recommends limiting this query to no more than once or twice per day.
To use the Failover API contact Bing Customer Service who can enable it for your account.

JSON

Query current list of failovers (since last reset):

http://easymail.com/publicinterface/failovers.json?account=ABC12345

Query current list of failovers (since last reset) and reset(clear) list:

http://easymail.com/publicinterface/failovers.json?_method=PUT&account=ABC12345&reset=true

JSON Response

[{
	"epid": " Q9VGGCHHM2Q7D68MJVMR9TDTGPQ4",
	"customer_reference": "20924",
	"dbid": 80712339,
	"failover_reason": "5.1.1: SMTP; 550 Requested action not taken: mailbox unavailable",
	"idx": 1,
	"failover_posix_ts": 1487720980,
	"failover_time": "22/02/2017 10:49:40",
	"transport": ["EMAIL",
	"POST"]
}]

XML

Query current list of failovers (since last reset):

http://easymail.com/publicinterface/failovers.xml?account=ABC12345

Query current list of failovers (since last reset) and reset(clear) list:

http://easymail.com/publicinterface/failovers.xml?_method=PUT&account=ABC12345&reset=true

Authentication is available using digest auth. Only enabled on request.

 
XML Response

<?xml version="1.0" encoding="UTF-8"?>
<ListFailoversResult>
	<FailoverLetter>
		<CustomerReference>20924</CustomerReference>
		<Reason>5.1.1: SMTP; 550 Requested action not taken: mailbox unavailable </Reason>
		<EPID>X2PPTRGDC7B89W7PXQDQ78DKHXVK</EPID>
		<index>1</index>
		<FailoverTime>24/08/2012 09:36:05</FailoverTime>
		<BingDBID>14376202</BingDBID>
		<FailoverPosixTS>1345764965</FailoverPosixTS>
	</FailoverLetter>
</ListFailoversResult>