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Exchange Online Protection Limits

Office 365
 

Topic Last Modified: 2014-07-21

The following limits currently exist for Exchange Online Protection. These limits are not configurable, unless specified otherwise.

TipTip:
For more information about limits in Exchange Online, see Exchange Online Limits. The transport rule limits also apply to EOP standalone customers. The recipient rate and message rate limits for Exchange Online are not applicable for EOP standalone customers.
  • Domain limit   You can add up to 900 domains per tenant. Subdomains can be included in this 900 limit, or if necessary, as part of a catch-all option, match subdomains. For more information, see Manage Accepted Domains in EOP.

  • Message size limit   The maximum message size for EOP standalone customers, including attachments, is 150 MB. The maximum message size for Exchange Enterprise CAL with Services and Exchange Online customers is 25 MB. These values apply to inbound and outbound messages.

  • Number of outbound messages sent   The limit for the number of outbound messages sent through EOP is high enough to ensure that normal email communication is not treated as spam. If you want to send commercial bulk email messages, rather than sending outbound messages through EOP, we recommend that you either use a third-party email service provider (ESP) or send them through your on-premises email servers.

  • Recipient limit   This is the maximum number of recipients allowed in the To:, Cc:, and Bcc: fields for a single email message. The maximum number of recipients that EOP customers can send a message to is 500.

  • IP Allow or IP Block list limit   When configuring an IP Allow list or an IP Block list in the connection filter, you can specify a maximum of 1273 entries, where an entry is either a single IP address or a CIDR range of IP addresses from /24 to /32.

  • Message deferral limit   Messages in deferral will remain in our queues for 2 days. Message retry attempts are based on the error type received from the recipient’s mail system. Messages are retried every 15 minutes.

  • Spam quarantine retention period   By default, spam messages sent to the quarantine are retained for 15 days. Administrators can lower this value via content filter policies.

  • End-user spam quarantine notifications   By default, if enabled, end-user spam quarantine notifications are sent every 3 days. They can be configured to be sent every 1 to 15 days.

  • Reporting and message trace limits   For reporting and message trace limits, see the “Reporting and message trace data availability and latency” section in Reporting and Message Trace in Exchange Online Protection.

 

Feature EOP Standalone EOP features in Exchange Online Exchange Enterprise CAL with Services

Domain limit

900

900

900

Message size limit (including attachments)

150 MB

25 MB

25 MB

Recipient limit

500 recipients

500 recipients

500 recipients

IP Allow or IP Block list limit

1273 entries

1273 entries

1273 entries

Message deferral limit

2 days, retried every 15 minutes

2 days, retried every 15 minutes

2 days, retried every 15 minutes

Spam quarantine retention period

15 days by default but can be lowered

15 days by default but can be lowered

15 days by default but can be lowered

End-user spam quarantine notifications

3 days by default, configurable from 1 to 15 days

3 days by default, configurable from 1 to 15 days

3 days by default, configurable from 1 to 15 days

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