In Message Tracking, messages will appear where the subject begins with “Message delivered via relay”. The reason for this is that the sending SMTP server requests a “Delivery Notification” in the SMTP envelope. However, these notifications are not supported by the receiving SMTP server. These notifications are requested via the NOTIFY parameter of the RCPT TO command, e.g.

RCPT TO:<> NOTIFY=Delay,Failure

Depending on the request this must be altered accordingly on the sending side or the receiving side. This behaviour cannot be changed by NoSpamProxy.

This article provides an overview of the versions currently covered by our support as well as information on general software requirements.

Please understand that in order to be eligible for support, you must have a contract in place.

General Requirements

It is not possible to operate NoSpamProxy in combination with Microsoft Exchange on a domain controller.

NoSpamProxy can be installed on a regular server in parallel with Exchange. However, this combination is not recommended, since duplicate port assignments often result in problems:

  • Port 6060/6061 TCP (internal communication between the roles of NoSpamProxy)
  • Port 25 (also used by Exchange)
  • Port 443 (required for the Web Portal but can be modified)


  • Version 13
  • Version 12.2
  • Version 12.1
  • Version 12.0
  • Version 11.1

NoSpamProxy Outlook Add-in

  • Outlook 2010 and later
  • Outlook 2007 (supported until June 30, 2019)

Microsoft Operating Systems

  • Microsoft Windows Server 2019
  • Microsoft Windows Server 2016
  • Microsoft Windows Server 2012 / R2
  • Microsoft Windows Server 2008 R2 (no longer supported as of version 13.1)

Microsoft .NET Framework

  • .NET Framework 4.7.2, mandatory as of NoSpamProxy 12.2
  • .NET Framework 4.6.2, supported up to version 12.1
  • .NET Framework 4.5.7, supported up to version 11.1

Microsoft SQL

  • Microsoft SQL Server 2017 incl. Express Version
  • Microsoft SQL Server 2014 incl. Express Version
  • Microsoft SQL Server 2012 incl. Express Version
  • Microsoft SQL Server 2008 R2 incl. Express version (no longer supported as of version 13.1)

Microsoft Report Viewer

For the installation of the Intranet Role the following tools are required:

  • Microsoft Report Viewer 2010

Microsoft Visual Studio Tools for Office

For the installation of the Outlook Add-In the following tools are required:

  • Visual Studio Tools for Office 2010 Runtime or later

If you want to run NoSpamProxy, or parts of it, in a virtual machine in a Microsoft Azure environment, you need an IP address that will be retained even after the machine restarts. To achieve this, you must set up a Reserved IP Address. If you fail to do this, there is a very good chance that a different IP address will be assigned after the machine restarts.

To set up a Reserved IP address, please use the information in the following Microsoft article:

This article explains how to check database integrity and repair it if necessary.

Microsoft SQL Server Management Studio is required to do this.

    1. Open Microsoft SQL Server Management Studio.
    2. Expand the Databases menu item.
    3. Click on the database “NoSpamProxyDB” and then on New Query in the upper left area. A white window now appears on the right side. To check a suspicious database for errors, you can use the following command in SQL Management Studio:
      DBCC CHECKDB ('NoSpamProxyDB')

    The next command would then correct these errors. You must set the Restrict Access mode from MULTI_USER to SINGLE_USER under Options in the database's Properties before running the command.

    The success is checked again with the following command.
    DBCC CHECKDB ('NoSpamProxyDB')

    No red error messages should appear in the output now. If the database could not be successfully repaired and red error messages still appear, execute the more aggressive command

    You should also check the success with the above command afterwards. If the database cannot be repaired, you can also create a new database via the NoSpamProxy interface. The point can be found under the node “Troubleshooting”.

    If problems with the SQL Server occur often, a defect on the SQL Server is likely.

If on-access virus scanners are used in combination with the integrated CYREN Premium antivirus problems may occur. To avoid any issues, please configure your virus scanner in such a way that the directories

C:\ProgramData\Net at Work Mail Gateway\CYREN


C:\ProgramData\Net at Work Mail Gateway\Temporary Files\MailQueues


C:\ProgramData\Net at Work Mail Gateway\Temporary Files\MailsOnHold

are exempted from scans on systems on which a Gateway Role or Web Portal is installed.

For servers running the Web Portal, the following folder (default path for storing the files for the WebPortal) must also be excluded:

C:\Program Files\Net at Work Mail Gateway\enQsig Webportal\App_Data\


If you do not find the path described above, it is most likely an older NoSpamProxy installation that has already had one or two updates. In this case, please first look into the file

C:\ProgramData\Net at Work Mail Gateway\Configuration\Gateway Role.config

and search for the entry

<storageLocation path=...

This path is currently used by the gateway role.

If you have enabled “File-based virus scanning” in the rules, please also make sure that your scanner is configured to completely delete or quarantine infected files and archives. If the scanner is configured to “Clean”, NoSpamProxy will in many cases not be able to detect that the installed scanner has changed the files, especially in the case of archives. The “File-based virus scan” will fail despite successful detection.

Office 365-relevant IP addresses

All IP addresses relevant for Office 365 integration in NoSpamProxy can be found at

Learn how to set up Office 365 in NoSpamProxy in our blog post NoSpamProxy integration in Office 365.

This article describes how to configure NoSpamProxy to store the decrypted data in a file before processing it in an email. This can be very helpful when analysing formatting problems related to encryption and decryption.

To create the encryption dump, proceed as follows:

The corresponding setting is made in the file “Gateway Role.config” in the directory “C:\ProgramData\Net at Work Mail Gateway\Configuration\”.

You must first search for the following line in the file:


Below this line, add the following line:

<debugging dumpDecryptedContentToDisk="true"/>

If the section “netatwork.nospamproxy.cryptography” already exists, simply add the following line:

<debugging dumpDecryptedContentToDisk="true"/>

Before you save the configuration file, you must stop the Gateway Role service. Only then can you save the configuration file correctly.

The decrypted contents are now stored in the Temp folder of the Local Service. Usually this is the folder C:\Windows\ServiceProfiles\LocalService\AppData\Local\Temp. If the files are not created there, please check the folder C:\Windows\Temp.

This article describes how to create a memory dump on a Windows 2008 Server R2 or later for use by the NoSpamProxy support team.

On the affected server, open the Task Manager and navigate to the Details tab and sort by Names.

Right-click on the corresponding process and select “Create dump file”.

Send the corresponding dump to the NoSpamProxy support team at