Do you have an old Hotmail or Yahoo email account that you haven't checked in years? Chances are good that all of those emails are gone forever. That's because both companies have deleted accounts that weren't used often enough.
Many companies have gotten much better about email retention and you can usually expect that your email will stick around for a long time. There's still one major problem: If you accidentally delete an email, then it might be gone forever.
Microsoft just switched up its data retention policy for Exchange Online email accounts. Now, companies that use Exchange Online email through Office 365 will never lose deleted emails by default.
While it might look like a lifesaver, this change might be required by law in the future.