Office 365, Email, Exchange, What are my Mailbox Size Limits?

What are my Mailbox Size Limits

Mailboxes for Users on the Exchange system have a hard limit of 100GB
Current Warnings:
  • 98GB: Warning regarding Inbox Size
  • 99GB: Unable to Send Email
  • 100GB: Unable to Send and Receive Email

Additionally users may experience performance issues when exceeding the following thresholds:

Total Mailbox Items: 250,000
Total Calendar Items: 5,000

For more information regarding Exchange Online Limits please check out this document: https://docs.microsoft.com/en-us/office365/servicedescriptions/exchange-online-service-description/exchange-online-limits