Exchange Server uses Receive Connectors for providing SMTP endpoints for incoming connections. A modern Exchange Server provides a default connector on TCP port 25.
Sometimes you might have a requirement to create a new receive connector for selected incoming SMTP connections. A standard requirement is a receive connector for relaying messages to external recipients. This cannot (should not) be achieved using the default connector.
Each connector uses the RemoteIPRanges attribute to store the list of IP addresses of remote systems that can connect to that connector. The default connector utilizes the full IPv4 and IPv6 addresses ranges.
Your new receive connector requires at least a single IP address for a selected remote system that is supposed to connect to that receive connector. You can add a single IP address, address ranges, or IP addresses using CIDR notation.
The attribute RemoteIPRanges is a multi-value attribute and has a limit of IP address entries that can be added.
The maximum number of address entries that you can add to that attribute varies. You can store approximately 1,300 entries.
When you exceed the number of values you receive the following error message:
The administrative limit for this request was exceeded. + CategoryInfo : NotSpecified: (:) [Set-ReceiveConnector], AdminLimitExceededException + FullyQualifiedErrorId : [Server=EX01,RequestId=ee9d45ad-418b-4172-9235-963eca1a7830,TimeStamp=18.08.2020 20:07:54] [FailureCategory=Cmdlet-AdminLimitExceededException] AC1E336E,Microsoft.Exchange.Management.SystemConfi gurationTasks.SetReceiveConnector + PSComputerName : ex01.varunagroup.de
I have tested the number of values that can be stored in that multi-value attribute. Depending on the IP address format I was able to add 1,238 (172.80.x.y) or 1,244 (10.1.x.y) single IP addresses to the RemoteIPRanges attribute.
Plan your IP address configuration requirements carefully and avoid using single IP addresses. Preferably, you should use IP address ranges or IP address CIDR notation for networks.
Enjoy Exchange Server!
Are you located in Germany, Austria, or Switzerland? Join the Exchange User Group DACH to collaborate with other Exchange enthusiasts.
Follow us on Twitter @exusg, join on Meetup, or visit our website.