Microsoft hits back at Delta after the airline said last month's tech outage cost it $500 million

Microsoft is joining cybersecurity software firm CrowdStrike in fighting back against Delta Air Lines, which blames the companies for causing several thousand canceled flights following a technology outage last month.

A lawyer for Microsoft said Tuesday that Delta's key IT system is probably serviced by other technology companies, not Microsoft Windows.

“Your letter and Delta’s public comments are incomplete, false, misleading, and damaging to Microsoft and its reputation,” Microsoft lawyer Mark Cheffo said in a letter to Delta attorney David Boies.

Cheffo said Microsoft was trying to determine “why other airlines were able to fully restore business operations so much faster than Delta.”