6 Appendix A: Product Behavior

The information in this specification is applicable to the following Microsoft products or supplemental software. References to product versions include updates to those products.

The terms "earlier" and "later", when used with a product version, refer to either all preceding versions or all subsequent versions, respectively. The term "through" refers to the inclusive range of versions. Applicable Microsoft products are listed chronologically in this section.

Windows Client

• Windows NT operating system

• Windows 2000 operating system

• Windows XP operating system

• Windows Vista operating system

• Windows 7 operating system

• Windows 8 operating system

• Windows 8.1 operating system

• Windows 10 operating system

• Windows 11 operating system

Windows Server

• Windows NT

• Windows 2000

• Windows Server 2003 operating system

• Windows Server 2008 operating system

• Windows Server 2008 R2 operating system

• Windows Server 2012 operating system

• Windows Server 2012 R2 operating system

• Windows Server 2016 operating system

• Windows Server operating system

• Windows Server 2019 operating system

• Windows Server 2022 operating system

• Windows Server 2025 operating system

Exceptions, if any, are noted in this section. If an update version, service pack or Knowledge Base (KB) number appears with a product name, the behavior changed in that update. The new behavior also applies to subsequent updates unless otherwise specified. If a product edition appears with the product version, behavior is different in that product edition.

Unless otherwise specified, any statement of optional behavior in this specification that is prescribed using the terms "SHOULD" or "SHOULD NOT" implies product behavior in accordance with the SHOULD or SHOULD NOT prescription. Unless otherwise specified, the term "MAY" implies that the product does not follow the prescription.

<1> Section 1.3.2.2: Windows support for generating and accepting message hashes is as follows.

<2> Section 1.3.4: Windows Server 2008 and later server operating systems, and Windows 7 and later client operating systems do not perform source journaling for messages sent to administration queues, notification queues, and order queues.

<3> Section 2.1: Windows NT, Windows 2000, Windows XP, and Windows Server 2003 use Ping Messages (section 2.1.2) to determine whether a server is available.

<4> Section 2.1.1: The SPX/IPX protocol is supported only on Windows NT and Windows 2000.

<5> Section 2.1.1: The Windows implementation utilizes the Windows Sockets API for TCP or SPX connections. The Windows Sockets API is responsible for operations such as selection of the source port used by an initiator and listening/accepting connections by the acceptor.

<6> Section 2.1.1: The Windows implementation utilizes the Windows Sockets API for TCP or SPX connections. The Windows Sockets API is responsible for operations such as selection of the source port used by an initiator and listening/accepting connections by the acceptor.

<7> Section 2.1.2: Windows NT, Windows 2000, Windows XP, and Windows Server 2003 use Ping Messages (section 2.1.2) to determine whether a server is available.

<8> Section 2.1.2: The IPX/SPX protocol is supported only on Windows NT and Windows 2000.

<9> Section 2.1.2: The port to which Ping Requests are sent is controlled by the registry key HKEY_LOCAL_MACHINE\software\microsoft\msmq\parameters\MsmqIpPingPort for Ping Requests sent using UDP or the registry key HKEY_LOCAL_MACHINE\software\microsoft\msmq\parameters\MsmqIpxPingPort for Ping Requests sent using SPX. The default port number 3527 is used when the corresponding key is absent.

<10> Section 2.1.2: Windows NT, Windows 2000, Windows XP, and Windows Server 2003 always listen for Ping Requests. Otherwise, Windows does not listen for Ping Requests by default, but listening for Ping Requests can be enabled by defining a registry key of type DWORD called HKEY_LOCAL_MACHINE\software\microsoft\msmq\parameters\security\EnablePingService and setting its value to 0x00000001.

<11> Section 2.1.2: The port on which an acceptor listens for Ping Requests is controlled by the registry key HKEY_LOCAL_MACHINE\software\microsoft\msmq\parameters\MsmqIpPingPort for Ping Requests sent using UDP or the registry key HKEY_LOCAL_MACHINE\software\microsoft\msmq\parameters\MsmqIpxPingPort for Ping Requests sent using SPX. The default port number 3527 is used when the corresponding key is absent.

<12> Section 2.2.1: On Windows NT, Windows 2000, Windows XP, and Windows Server 2003, the acceptor refuses the connection when the number of open connections exceeds the number of Client Access Licenses (CALs). Multiple connections from the same initiator are counted as one. On Windows Vista and later client operating systems, and Windows Server 2008 and later server operating systems, the acceptor does not verify access licenses. The acceptor also refuses the connection when the maximum number of sessions has been reached. The value for the maximum number of sessions can be set in the registry key HKEY_LOCAL_MACHINE\software\microsoft\msmq\parameters\MaxInSessions. When this key is absent, the default maximum is 0xFFFFFFFF.

<13> Section 2.2.3.1: This parameter is used to implement client access licensing restrictions by Windows NT, Windows 2000, Windows XP, and Windows Server 2003. It is ignored by Windows Vista and later client operating systems, and Windows Server 2008 and later server operating systems.

<14> Section 2.2.3.1: The Windows implementation calls the GetVersionEx() Win32 API to determine client or server platform.

<15> Section 2.2.3.1: The EstablishConnectionHeader.OperatingSystem.QS bit field value does not affect the transport settings. The Guaranteed Quality of Service (GQoS) values exchanged are only informational.

<16> Section 2.2.4: The IPX/SPX protocol is supported only on Windows NT.

<17> Section 2.2.4.1: The Windows implementation can leave this field uninitialized; hence, it can contain arbitrary data when the OrderAck Packet (section 2.2.4) is sent. This field is ignored when the OrderAck Packet is received.

<18> Section 2.2.5: The IPX/SPX protocol is supported only on Windows NT.

<19> Section 2.2.7: The unused fields are uninitialized data in the Windows implementation.

<20> Section 2.3: For Windows NT and Windows 2000, this protocol uses the Message Queuing (MSMQ): Directory Service Protocol [MS-MQDS].

<21> Section 2.3: For the Message Queuing (MSMQ): Directory Service Protocol [MS-MQDS], the Directory Service schema elements are described in [MS-MQDS] sections 2.2.10 and 3.1.4.21.1 through 3.1.4.21.4.

<22> Section 3.1.1.3: The ReceiveBaseSymmetricKeyCache ADM element is used only by Windows 2000, Windows XP, and Windows Server 2003. None of these enforces time-out of the CachedSymmetricKey (section 3.1.1.3.3) ADM element instances in this list; therefore, there is no ReceiveBaseSymmetricKeyCache Cleanup Timer or associated event, where one might be expected by analogy with the ReceiveSymmetricKeyCache ADM element.

<23> Section 3.1.1.3: The SendBaseSymmetricKeyCache ADM element is used by Windows 2000, Windows XP, and Windows Server 2003.

<24> Section 3.1.1.3: The Windows default time-out is 30 seconds. The time-out grows as the number of sequential time-outs increases. The first, second, and third time-outs have periods of 30 seconds. The fourth, fifth, and sixth time-outs are 5 minutes. The seventh, eighth, and ninth time-outs are 30 minutes, and thereafter, the time-out period is 6 hours.

Windows provides a registry key at HKEY_LOCAL_MACHINE\software\microsoft\msmq\parameters\SeqResend13Time that can be used by the client to specify different resend times in seconds beyond the default values for the first, second, and third time-outs.

Windows provides a registry key at HKEY_LOCAL_MACHINE\software\microsoft\msmq\parameters\SeqResend46Time that can be used by the client to specify different resend times in seconds beyond the default values for the fourth, fifth, and sixth time-outs.

Windows provides a registry key at HKEY_LOCAL_MACHINE\software\microsoft\msmq\parameters\SeqResend79Time that can be used by the client to specify different resend times in seconds beyond the default values for the seventh, eighth, and ninth time-outs.

Windows provides a registry key at HKEY_LOCAL_MACHINE\software\microsoft\msmq\parameters\SeqResend10Time that can be used by the client to specify a different resend time in seconds beyond the default value for the tenth time-out.

<25> Section 3.1.1.3: Windows sets the maximum size of the MessageIDHistoryTable ADM element to RemoveDuplicateSize. The RemoveDuplicateSize value is contained in the registry key at HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\MSMQ\Parameters\RemoveDuplicateSize. If the registry key does not exist, the RemoveDuplicateSize value is 10,000.

<26> Section 3.1.1.3: Windows performs no special action when the MessageIdOrdinal ADM element value rolls over. Values are reused after the rollover; however, the rollover condition does not affect message delivery guarantees because the MessageIDHistoryTable ADM element length is sufficiently short.

Windows persistently stores up to the last RemoveDuplicateSize MessageIDHistoryEntry ADM element values. The RemoveDuplicateSize value is contained in the registry key at HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\MSMQ\Parameters\RemoveDuplicateSize. If the registry key does not exist, the RemoveDuplicateSize value is 10,000.

Windows removes expired entries from the MessageIDHistoryTable ADM element every RemoveDuplicateCleanup milliseconds. The RemoveDuplicateCleanup value is contained in the registry key at HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\MSMQ\Parameters\RemoveDuplicateCleanup. If the registry key does not exist, the RemoveDuplicateCleanup value is 30 * 60 * 1000 (30 minutes).

<27> Section 3.1.1.3: Windows initializes the PingCookie ADM element to 0x00000000 when the queue manager is started and increments it by 1 before each Ping Request, as defined in Ping Message (section 2.1.2), is sent.

<28> Section 3.1.1.3: For Windows NT, Windows 2000, Windows XP, Windows Server 2003, and Windows Vista, the SendInsecureNacks ADM element is always TRUE. For Windows Vista operating system with Service Pack 1 (SP1) and later operating systems, and Windows Server 2008 and later server operating systems, the Windows implementation sets this value based on a registry key of type DWORD called HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\MSMQ\Parameters\Security\PermitInsecureNacks. The SendInsecureNacks ADM element is TRUE if the registry key value is 0x00000001 and FALSE if the registry key value is set to 0x00000000 or the registry key does not exist. By default, the registry key does not exist.

<29> Section 3.1.1.3: The SendInsecureNacks ADM element is saved to persistent storage for Windows Vista SP1 and later client operating systems, and for Windows Server 2008.

<30> Section 3.1.1.3: Windows provides a registry key at HKEY_LOCAL_MACHINE\software\microsoft\msmq\parameters\SeqResend13Time that can be used by the client to specify a different value in seconds.

<31> Section 3.1.1.3: Windows provides a registry key at HKEY_LOCAL_MACHINE\software\microsoft\msmq\parameters\SeqResend46Time that can be used by the client to specify a different value in seconds.

<32> Section 3.1.1.3: Windows provides a registry key at HKEY_LOCAL_MACHINE\software\microsoft\msmq\parameters\SeqResend79Time that can be used by the client to specify a different value in seconds.

<33> Section 3.1.1.3: Windows provides a registry key at HKEY_LOCAL_MACHINE\software\microsoft\msmq\parameters\SeqResend10Time that can be used by the client to specify a different value in seconds.

<34> Section 3.1.1.3.1: Each Windows client and server generates a unique GUID ([MS-DTYP] section 2.3.4) upon setup and stores it durably as a binary value under the HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\MSMQ\Parameters\MachineCache\QMId registry key.

<35> Section 3.1.1.3.1: Windows sets the timestamp to the time of the queue manager installation or the last system restore. The value is the number of seconds elapsed since midnight (00:00:00), January 1, 1970 (Coordinated Universal Time (UTC)).

<36> Section 3.1.1.3.1: Windows sets the WindowSize ADM element to the maximum allowed value, which can be configured by setting a value in the registry key HKEY_LOCAL_MACHINE\software\microsoft\msmq\parameters\MaxUnackedPacket. When this key is absent, the default maximum is 64.

<37> Section 3.1.1.3.1.3: Each Windows client and server generates a unique GUID ([MS-DTYP] section 2.3.4) upon setup and stores it durably as a binary value under the HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\MSMQ\Parameters\MachineCache\QMId registry key.

<38> Section 3.1.1.6.1: Windows discards express, recoverable, and transactional messages that have been acknowledged.

<39> Section 3.1.1.6.1: Windows discards express, recoverable, and transactional messages that have been acknowledged.

<40> Section 3.1.1.6.2: Windows discards express, recoverable, and transactional messages that have been acknowledged.

<41> Section 3.1.1.7.1: Only Windows NT, Windows 2000, Windows XP, and Windows Server 2003 utilize the Ping Message (section 2.1.2) mechanism.

<42> Section 3.1.1.7.1: Windows NT, Windows 2000, Windows XP, and Windows Server 2003 always respond to Ping Requests, as defined in Ping Message (section 2.1.2). Otherwise, Windows does not respond to Ping Requests by default, but Ping Responses, as specified in section 2.1.2, can be enabled by defining a registry key of type DWORD called HKEY_LOCAL_MACHINE\software\microsoft\msmq\parameters\security\EnablePingService and setting its value to 0x00000001.

<43> Section 3.1.2.1: The Microsoft implementation sets the Session Initialization Timer (section 3.1.2.1) to a value in milliseconds equal to 60000 + (2 * RoundTripDelay). The RoundTripDelay value is contained in the registry key at HKEY_LOCAL_MACHINE\software\microsoft\msmq\parameters\RoundTripDelay. If the registry key does not exist, zero is used for the RoundTripDelay value.

<44> Section 3.1.2.2: The Windows default value for the Session Cleanup Timer (section 3.1.2.2) is 300,000 milliseconds. If the queue manager is a routing server, the default value for the Session Cleanup Timer is 120,000 milliseconds. This default value can be overridden by setting the registry key HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\MSMQ\Parameters\CleanupInterval to the desired value, in milliseconds.

<45> Section 3.1.2.3: The Windows default reconnection time-out is 5,000 milliseconds unless otherwise specified in milliseconds in the registry key HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\MSMQ\Parameters\TryConnectInterval. Additionally, the value in milliseconds, if any, in the registry key HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\MSMQ\Parameters\RoundTripDelay is also added to the reconnection time-out.

<46> Section 3.1.2.4: For sessions established for a direct format name, this value is read from the registry key HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\MSMQ\Parameters\QosCleanupIntervalMultiplier that is of type DWORD. When this key is absent, the factor defaults to 2 for sessions established for direct format names. The default multiplying factor is 1 for sessions not established for direct format names.

<47> Section 3.1.2.8: The Windows default timeout is 30 * 60 * 1000 milliseconds (30 minutes). This default value can be overridden by setting the registry key HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\MSMQ\Parameters\RemoveDuplicateCleanup to the desired value, in milliseconds.

<48> Section 3.1.3.1: For Windows NT, the SendEnhancedRC2Using40BitKeys ADM element is always FALSE. For Windows 2000, Windows 2000 operating system Service Pack 1 (SP1), Windows 2000 operating system Service Pack 2 (SP2), Windows 2000 operating system Service Pack 3 (SP3), and Windows XP, the SendEnhancedRC2Using40BitKeys ADM element is always TRUE. For Windows 2000 operating system Service Pack 4 (SP4), the default value is TRUE. For Windows XP operating system Service Pack 1 (SP1), Windows XP operating system Service Pack 2 (SP2), Windows XP operating system Service Pack 3 (SP3), and Windows Server 2003, the default value is FALSE. For Windows Vista and later client operating systems, and Windows Server 2008 and later server operating systems, the SendEnhancedRC2Using40BitKeys ADM element is always FALSE.

<49> Section 3.1.3.1: For Windows NT, the RejectEnhancedRC2Using40BitKeys ADM element is always TRUE. For Windows 2000, Windows 2000 SP1, Windows 2000 SP2, Windows 2000 SP3, and Windows XP, the RejectEnhancedRC2Using40BitKeys ADM element is always FALSE. For Windows 2000 SP4 and later server operating systems, and for Windows XP SP1, and later client operating systems, the default value is FALSE.

<50> Section 3.1.3.2: Windows sets the WindowSize ADM element value to the maximum allowed value. The maximum allowed value of this field can be configured by setting a value in the registry key HKEY_LOCAL_MACHINE\software\microsoft\msmq\parameters\MaxUnackedPacket. When this key is absent, the default maximum is 64.

<51> Section 3.1.3.2: The default setting is 20,000 milliseconds on a local area network (LAN). The Microsoft implementation provides a registry key at HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\MSMQ\Parameters\RoundTripDelay that the client uses to specify additional time beyond the default value.

<52> Section 3.1.3.2: The value of the MaximumOrderAckDelay ADM element is contained in the registry key HKEY_LOCAL_MACHINE\software\microsoft\msmq\parameters\SeqMaxAckDelay. If the registry key does not exist, the value of the MaximumOrderAckDelay ADM element is 10 seconds.

<53> Section 3.1.3.2: Each Windows client and server generates a unique GUID ([MS-DTYP] section 2.3.4) upon setup and stores it durably as a binary value under the HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\MSMQ\Parameters\MachineCache\QMId registry key.

<54> Section 3.1.3.2: The Windows default value is 0x00000000.

<55> Section 3.1.5.2.1: The Windows implementation performs the host address resolution each time that a protocol session is established to the destination host computer. A protocol session can be used to send multiple messages to the destination host; however, the host address is queried only once when the protocol session is established.

The Windows implementation of this protocol uses the Winsock APIs to obtain a list of addresses corresponding to the destination host name.

<56> Section 3.1.5.2.2: The Ping Packet (section 2.2.7) mechanism is utilized by Windows NT, Windows 2000, Windows XP, and Windows Server 2003 when connecting to remote queue managers.

<57> Section 3.1.5.3.1: On Windows NT, Windows 2000, Windows XP, and Windows Server 2003, the acceptor refuses the connection when the number of open connections exceeds the number of Client Access Licenses (CALs). Multiple connections from the same initiator are counted as one.

<58> Section 3.1.5.8.3: For Windows NT, Windows 2000, Windows XP, or Windows Server 2003, if the MessagePropertiesHeader.PrivacyLevel field has the value 0x00000005, the message is rejected using the same steps as for PrivacyLevel values that do not appear in the table.

<59> Section 3.1.5.8.3: Windows 2000, Windows XP, and Windows Server 2003 search the ReceiveBaseSymmetricKeyCache ADM element if the MessagePropertiesHeader.PrivacyLevel field is 0x00000001 and search the ReceiveSymmetricKeyCache ADM element if the MessagePropertiesHeader.PrivacyLevel field is 0x00000003.

<60> Section 3.1.5.8.3: Windows 2000, Windows XP, and Windows Server 2003 add the CachedSymmetricKey ADM element instance to the ReceiveBaseSymmetricKeyCache ADM element if the MessagePropertiesHeader.PrivacyLevel field is 0x00000001 or to the ReceiveSymmetricKeyCache ADM element if the MessagePropertiesHeader.PrivacyLevel field is 0x00000003.

<61> Section 3.1.5.8.3: Windows NT, Windows 2000, Windows XP, Windows Server 2003, Windows Vista, and Windows Server 2008 do not start the ReceiveSymmetricKeyCache Cleanup Timer (section 3.1.2.10).

<62> Section 3.1.5.8.10: Windows Server 2008 and later server operating systems, and Windows 7 and later client operating systems, do not send administration acknowledgments for messages sent to administration queues, notification queues, and order queues.

<63> Section 3.1.6.11: Windows XP and Windows Server 2003 use the SymmetricKeyLongLifetime ADM element instead of the SymmetricKeyShortLifetime ADM element when calculating whether a CachedSymmetricKey ADM element instance has expired.

<64> Section 3.1.6.11: Windows XP and Windows Server 2003 use the SymmetricKeyLongLifetime ADM element instead of the SymmetricKeyShortLifetime ADM element when calculating the duration with which to restart the SendSymmetricKeyCache Cleanup Timer (section 3.1.2.11).

<65> Section 3.1.7.1.5: If the remote queue manager identified by the RemoteQMGuid ADM element is Windows NT, Windows 2000, Windows XP, or Windows Server 2003, there are only two MQDSPUBLICKEY ([MS-MQMQ] section 2.2.1) structures, with sProviderName field values of "Microsoft Base Cryptographic Provider v1.0" and "Microsoft Enhanced Cryptographic Provider v1.0".

<66> Section 3.1.7.1.5: Windows NT, Windows 2000, Windows XP, or Windows Server 2003 select a CSP, encryption algorithm, and symmetric key length according to these steps:

• If Message.PrivacyLevel is Base, UseCSP is set to "Microsoft Base Cryptographic Provider 1.0", and UseSymmKeyLength is set to 40.

• If Message.PrivacyLevel is Enhanced, UseCSP is set to "Microsoft Enhanced Cryptographic Provider 1.0", and UseSymmKeyLength is set to 128. If Message.EncryptionAlgorithm is RC2 and SendEnhancedRC2Using40BitKeys is TRUE, UseSymmKeyLength is set to 40.

• If Message.PrivacyLevel is Advanced, the steps in section 3.1.7.1.5.1 are performed.

• UseAlgorithm is set according to the value of Message.EncryptionAlgorithm:

  Message.EncryptionAlgorithm	UseAlgorithm Value
  RC2	0x00006602
  RC4	0x00006801

• Search the MQDSPUBLICKEYS ([MS-MQMQ] section 2.2.2) structure in the RemoteQMPublicKey ADM element for an  MQDSPUBLICKEY ([MS-MQMQ] section 2.2.1) structure where the sProviderName field is equal to the value of UseCSP, and set UsePublicKey to the PUBLICKEYBLOB (section 2.4.1) that results when the abuf field of the MQDSPUBLICKEY structure is processed according to the steps in section 3.1.7.1.5.2. If no MQDSPUBLICKEY structure is found, perform the steps in section 3.1.7.1.5.1.

<67> Section 3.1.7.1.5: Windows 2000, Windows XP, and Windows Server 2003 search the SendBaseSymmetricKeyCache ADM element if UseCSP is "Microsoft Base Cryptographic Provider v1.0".

<68> Section 3.1.7.1.5: Windows 2000, Windows XP, and Windows Server 2003 add the CachedSymmetricKey (section 3.1.1.3.3) ADM element instance rCachedSymmetricKey to the SendBaseSymmetricKeyCache ADM element if UseCSP is "Microsoft Base Cryptographic Provider v1.0".

<69> Section 3.1.7.1.5: Windows 2000, Windows XP, and Windows Server 2003 start the SendBaseSymmetricKeyCache Cleanup Timer (section 3.1.2.12) with a duration of the value of the SymmetricKeyShortLifetime ADM element if the newly created CachedSymmetricKey (section 3.1.1.3.3) ADM element instance rCachedSymmetricKey was added to the SendBaseSymmetricKeyCache ADM element and the timer is not already running. Windows XP and Windows Server 2003 start the SendSymmetricKeyCache Cleanup Timer (section 3.1.2.11) with a duration of the value of the SymmetricKeyLongLifetime ADM element if the newly created CachedSymmetricKey ADM element instance rCachedSymmetricKey was added to the SendSymmetricKeyCache ADM element and the timer is not already running.

<70> Section 3.1.7.7: On Windows NT, Windows 2000, and Windows XP, the acceptor refuses the connection when the number of open connections exceeds the number of Client Access Licenses (CALs). Multiple connections from the same initiator are counted as one. On Windows Vista and later client operating systems, and Windows Server 2008 and later server operating systems, the acceptor does not verify access licenses. Except on Windows NT, the acceptor also refuses the connection when the maximum number of sessions has been reached. The value for the maximum number of sessions can be set in the registry key HKEY_LOCAL_MACHINE\software\microsoft\msmq\parameters\MaxInSessions. When this key is absent, the default maximum is 0xFFFFFFFF.