Microsoft will require companies to file individual claims if they want a service credit for the Exchange Online outage of last month, the company said.
"If it's determined that the service didn't meet [the 99.9% uptime] bar in a particular month, we'll work with customers to credit them appropriately," a Microsoft spokesperson said in an email reply to questions. "This is on a case by case basis given the impact of service issues can vary among customers."
Two weeks ago today, Exchange Online went dark for many North American customers. The outage, which affected an unknown number of companies and users, was characterized as an "email delay" by Microsoft at the time. Some U.S. customers in the Eastern and Central time zones were unable to send or receive email for much of the business day on June 24.
Exchange Online is an off-premises service bundled with most Office 365 business plans, and is also offered separately. It has been a key component in Microsoft's attempt to convince enterprises to adopt the "rent-not-own" software subscription service and shift more of their back-office infrastructure to Microsoft-run data centers.
Three days later, Microsoft blamed a "unique" failure coupled with a previously unknown code flaw for the outage. During the downtime, the Office 365 status system -- the Service Health Dashboard (SHD), available only to IT administrators -- also blithely told some customers that all was well when in fact their email wasn't working.
Since then, Microsoft has said nothing publicly of the outage.
It has, however, as is its normal practice, provided Office 365 enterprise customers with a "Post Incident Review" (PIR) report. Computerworld has viewed the report, issued last week.
According to Microsoft, the outage officially began at 10 a.m. ET and ended at 5 p.m. ET, for an event 7 hours long.
That length of time is important because it's used in the calculations customers must make to figure out if Microsoft did or did not meet its promised 99.9% uptime.
In its service level agreement, or "SLA" (download Microsoft Word document), Microsoft provides a formula that customers must use to determine whether credits will be awarded. The formula is based on the number of users, the number affected, the outage's duration, and the amount of minutes in a given month.
Computerworld plugged numbers into that formula representing a company with 500 users, all of whom were affected by the outage, and calculated that the Exchange Online incident reduced June's uptime to 99.03%. If only 100 of the firm's 500 users had been affected, the uptime for the month would have been 99.903%.
According to the Office 365 SLA, an uptime less than 99.9% but greater than 99% means customers are eligible for a 25% service credit for that month's bill.
Or at least that part of the bill that Microsoft says was for the Exchange Online service. "If you purchased Services as part of a suite or other single offer, the Applicable Monthly Service Fees and Service Credit for each Service will be pro-rated," the SLA states.
Although Microsoft in the past has proactively handed out service credits to all affected customers -- it did just that after a pair of Exchange Online outages in November 2012 -- it appeared it will require companies to submit claims for the latest incident. The claims process, as spelled out in the SLA, requires customers to describe the event; identify the duration of their outage, the number and location(s) of affected users; and spell out what they did, if anything, to resolve the outage.
Those claims must be submitted to Microsoft by the end of July for the June 24 outage.
Also in the PIR report, Microsoft gave more information on the cause of the service interruption, saying, "Investigation determined that a portion of Exchange Online directory infrastructure was in a degraded state, causing impact to Exchange Online Protection mail flow."
In other words, messages got stuck in the Exchange Online Protection (EOP) queue. EOP is Microsoft's spam filtering service for cloud-based Exchange accounts.
Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter at @gkeizer, on Google+ or subscribe to Gregg's RSS feed . His email address is firstname.lastname@example.org.