Attackers often target email accounts because the messages and attachments can contain extremely sensitive information that can be used as leverage to extort the victim, or can be sold to people with criminal intent to misuse the private information for personal financial gain—for example, insider trading. While legislators and other government officials are often targeted, the email messages from global corporations are also highly sought-after by data thieves for the valuable information that they contain. All organizations that use email should protect access through strong password requirements and strictly enforced multi-factor authentication. If using cloud service providers such as Office 365, IT administrators must ensure that “legacy authentication” has been completely disabled to prevent attackers from bypassing the multi-factor authentication requirements.

Source: https://www.bleepingcomputer.com/news/security/hackers-breached-norwegian-parliament-emails-to-steal-data/