HOSTED MICROSOFT® EXCHANGE®

Exchange Online Limits

Find the Exchange Online limits for a variety of service areas, including address book limits, mailbox storage limits, and reporting and message trace limits, to name just a few.

The limits in Microsoft Exchange Online fall into one of the following categories:

Why the Cloud?

Address list limit1000
Offline address book (OAB) limit250
Address book policies (ABP) limit250
Global address lists limit250

Mailbox folder limits across Hosted Exchange options

Maximum number of messages per mailbox folder1 million
Warning for number of messages per mailbox folder900,000
Maximum number of messages per folder in the Recoverable Items folder3 million
Warning for number of messages per folder in the Recoverable Items folder2.75 million
Maximum number of subfolders per mailbox folder10,000
Warning for number of subfolders per mailbox folder900
Maximum folder hierarchy depth300
Warning for folder hierarchy depth250
Maximum number of public folders100,000
Maximum number of subfolders per public folder1,000
Warning for number of subfolders per public folder900

Message limits

Message size limit – Outlook50MB
Message size limit – OWA50MB
Message size limit – Outlook for Mac35 MB
Message size limit – migration50MB
Subject length limit255 characters
File attachments limit250 attachments
File attachment size limit – Outlook50MB
File attachment size limit – OWA25 MB
File attachment size limit – Outlook for Mac35 MB
Multipart message limit250 parts
Embedded message depth limit30 embedded messages

Recipient and sender limits

Recipient rate limit10,000 recipients per day
Recipient limit500 recipients

Retention limits

Deleted Items folder retention periodNo limit
Retention period for items removed from the Deleted Items folder14 days
Junk Email folder retention period30 days

Distribution group limits

Maximum number of distribution group members100,000 members
Limit sending messages to large distribution group5,000 or more members
Maximum message size for large distribution groups10 MB

Exchange ActiveSync limits

Exchange ActiveSync device limit100
Exchange ActiveSync device deletion limit20
Exchange ActiveSync file attachment limit25 MB
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