The following limits are built-in limitations to Office 365’s systems:
- Address List: 1000
- Mail Storage: 50 Gigabytes
- Messages per Mail Folder: 1 Million
- Message Size:
- Outlook (Windows): 150 Megabytes
- Outlook (Web): 112 Megabytes
- Outlook (Mac): 35 Megabytes
- Attachment Size:
- Outlook (Windows): 150 Megabytes
- Outlook (Web): 112 Megabytes
- Outlook (Mac): 35 Megabytes
- Mail Recipient Rate Limit: 10,000 messages per day
- Maximum Recipients per message: 500
- Mail Sending Rate Limit: 30 messages per minute
- Maximum number of Distribution Group members (currently disabled): 100,000