They say it has left them unable to access bank accounts and job offers - and stopped them using Skype, which Microsoft owns, to contact relatives in war-torn Gaza.
Microsoft says they violated its terms of service - a claim they dispute.
“They killed my life online,” said Eiad Hametto, who lives in Saudi Arabia.
“They’ve suspended my email account that I’ve had for nearly 20 years - It was connected to all my work,” he told the BBC.
He also said being cut off from Skype was a huge blow for his family.
The internet is frequently disrupted or switched off there because of the Israeli military campaign - and standard international calls are very expensive.
Israel launched its offensive in Gaza in response to the Hamas attack on 7 October, which killed about 1,200 people. The Hamas-run health ministry in Gaza says more than 38,000 people have been killed in the war.
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Palestinians calling home to Gaza on Skype have had their digital lives destroyed, after Microsoft closed their email accounts without warning.
BBC News has spoken to 20 Palestinians living abroad who say Microsoft, which owns the voice and video chat app, kicked them out of their accounts.
The Gazans say they have no links to Hamas - designated as a terrorist organisation by some Western countries, including the US, where Microsoft is headquartered - and accuse the technology giant, the most valuable company in the world, of persecuting them unfairly.
Salah Elsadi is living in the US and, like many Palestinians abroad, was using Skype to call his wife, children and parents on their mobile phones in Gaza.The internet is frequently disrupted or switched off because of the Israeli military campaign - and standard international calls are very expensive.
With a paid Skype subscription, it is possible to call mobiles in Gaza cheaply - and while the internet is down - so it has become a lifeline to many Palestinians.
But many of those BBC News has spoken to say they have tried many times and are receiving the same blanket response.One, Khalid Obaied, has lost faith with Microsoft.
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