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.
@PhlubbaDubba @tardigrada You still need email for pretty much most services. You need to log in? Create an account using your email and password. Need to work somewhere? A phone number is essential, but the employers will also use your email to message you if you cannot be reached on the phone (happened to me once) or when sending video call invites.
WhatsApp is ubiquitous when it comes to chatting, but for more elaborate communications, email still rules.