Set Connection Limits for IMAP4

Applies to: Exchange Server 2013, Exchange Online

Topic Last Modified: 2012-11-28

You can use the EAC or the Shell to manage IMAP4 connection limits for your organization.

When you specify connection limits for IMAP4, you can select connection limits for the server, an IP address, or a specific user.

For additional information related to IMAP4, see POP3 and IMAP4.

What do you need to know before you begin?

Estimated time to complete: 5 minutes.
You need to be assigned permissions before you can perform this procedure or procedures. To see what permissions you need, see the "IMAP4 settings" entry in the Clients and Mobile Devices Permissions topic.
For information about keyboard shortcuts that may apply to the procedures in this topic, see Keyboard Shortcuts in the Exchange Admin Center.

Tip:
Having problems? Ask for help in the Exchange forums. Visit the forums at: Exchange Server, Exchange Online, or Exchange Online Protection.

What do you want to do?

Use the EAC to set IMAP4 connection limits for a server, an IP address, or a user

In the EAC, navigate to Servers > Servers.
In the list of servers, select the Client Access server, and then click Edit .
On the server properties page, click IMAP4.
Scroll down and click More options.
Under Connection limits, use the following settings:
- Maximum connections Specifies the total number of connections the specified server will accept. This includes authenticated and unauthenticated connections. The default value is 2,147,483,647. The possible values are from 1 through 2,147,483,647.
- Maximum connections from a single IP address Specifies the number of connections that the server will accept from a single IP address. The default value is 2,147,483,647. The possible values are from 1 through 2,147,483,647.
- Maximum connections from a single user Specifies the maximum number of connections that the server will accept from a particular user. The default value is 16. The possible values are from 1 through 2,147,483,647.
- Maximum command size (bytes) Specifies the maximum size of a single command. The default size is 10,240. The possible values are from 1,024 through 16,384.
Click Apply, and then click OK to save your changes.

After you set connection limits, you must restart the IMAP4 services. For information about how to restart the IMAP4 services, see Start and Stop the IMAP4 Services.

Use the Shell to set IMAP4 connection limits for a server, an IP address, or a user

This example sets the connection limit for a server.

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Set-ImapSettings -Identity CAS01 -MaxConnections Value

This example sets the connection limit for an IP address.

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Set-ImapSettings -Identity CAS01 -MaxConnectionsFromSingleIP Value

This example sets the connection limit for a user.

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Set-ImapSettings -MaxConnectionsPerUser Value

This example sets the maximum command size.

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Set-ImapSettings -MaxCommandSize Value

After you set connection limits, you must restart the IMAP4 services. For information about how to restart the IMAP4 services, see Start and Stop the IMAP4 Services.

For more information about syntax and parameters, see Set-ImapSettings.

How do you know this worked?

To verify that you’ve successfully set connection limits, do one of the following:

In the EAC, navigate to Servers > Servers.
In the list of servers, select the Client Access server, and then click Edit .
On the server properties page, click IMAP4.
Scroll down and click More options.
Under Connection limits, verify the connection settings are correct.

Run the following command in the Shell.
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Get-ImapSettings | format-list
Verify the connection settings are correct.

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Get-ImapSettings \| format-list

For more information

After you set IMAP4 connection limits for a server, IP address, or a user, you may also want to:

Enable IMAP4 in Exchange 2013

Set Connection Time-Out Limits for IMAP4