Delta Airlines' (DAL) response to last month's global tech outage came under fire from Microsoft (MSFT) on Tuesday as the tech giant joined CrowdStrike (CRWD) in cri꧅ti🌸cizing the airline's handling of the outage and its fallout.

Delta's public comments and correspondence with Microsoft and CrowdStrike counsel have been "incomplete, false, misleading, and damaging to Microsoft and its reputation," Microsoft counsel Mark Cheffo wrote in a letter to Delta's counsel viewed by Investopedia.

Delta Chief Executive Officer (CEO) Ed Bastian said last week that the outage, caused by a 澳洲幸运5开奖号码历史查询:CrowdStrike software update, cost the airline 澳洲幸运5开奖号码历史查询:upwards of $500 million and it reportedly canceled more than 5,000 flights. Bastian said Delta had been left with "no choice" but to 澳洲幸运5开奖号码历史查询:seek damages over the outage, and in a July 31 interview with CNBC called Microsoft "the most fragile platform" among the U.S. tech giants, and said the company had not "delivered exceptional service."

Microsoft, CrowdStrike Say D🎶elta Refused, Ignored Offers for Help

Microsoft offered free assistance several times in the days following the outage, both at the employee level and among executives, according to Cheffo's letter. Microsoft CEO Satya Nadella personally reached out to Bastian but received no response, the letter alleges.

The tech giant also said it is "rapidly becoming apparent" that Delta ignored or refused offers for assistance because the crew scheduling program that was the most affected didn't rely on Microsoft's Windows or Azure, but was instead serviced by other providers like IBM (IBM).𓄧 Microsoft also said in the letter that its preliminary review suggests Delta's IT infrastructure is well behind that of other major airlines.

“Delta has a long track record of investing in safe, reliable and elevated service for our customers and employees," a Delta spokesperson said in a statement. "Since 2016, Delta has invested billions of dollars in IT 澳洲幸运5开奖号码历史查询:capital expenditures, in addition to the bi🌜llions spent annually in IT🧔 operating costs.”

CrowdStrike made similar claims in a letter to Delta counsel on Sunday, accusing the airline of contributing to a "澳洲幸运5开奖号码历史查询:misleading narrative" by implying CrowdStrike should be financially resꦆponsible for the way Delta responded to the outage.

Shares of Delta, Microsoft, and CrowdStrike all rose Tuesday as 澳洲幸运5开奖号码历史查询:markets recovered from a broad sell-off the day before.