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Getting Started with Exchange Connector

System Requirements

  • Microsoft .NET Framework 4.0
    After installing the .NET Framework, we strongly recommend running Windows Update and installing the latest Important and Optional updates. Note that .NET Framework 4.5 includes the required .NET Framework 4.0 components.
  • Microsoft Exchange Server 2013 with Mailbox Role, 2010/2007 with Hub Transport Role, or Exchange 2003
    The latest service pack for Exchange is recommended, as are multi-Role Exchange Servers.
  • Windows Server 2012, 2008 R2, 2008, 2003 R2 or 2003
    Both 32-bit (x86) and 64-bit (x64) versions of Windows are supported. If installing Exchange Connector on the same machine as the Exchange server, the platform requirements of the version of Exchange need to be considered. Specifically, as 32-bit versions of Exchange 2007 and later are not supported by Microsoft for production use, they are not supported for production use with Exchange Connector. The operating system and platform architecture (32-bit or 64-bit) do not need to match if Exchange Connector is installed on a separate machine to Exchange. Desktop operating systems (Windows XP, Windows Vista, Windows 7 and Windows 8) are not supported by Exchange Connector for production use.

    The latest service pack for Windows is recommended. For Windows Server 2003 and Windows Server 2003 R2, a minimum of SP2 is recommended. For Windows Server 2008 and Windows Server 2008 R2, a minimum of SP2 is recommended.

Installing Exchange Connector

Download the appropriate version for the platform you are using (32-bit or 64-bit). In an Exchange 2013 environment, we recommend installing Exchange Connector on a server with the Mailbox Role. In an Exchange 2010 or 2007 environment, we recommend installing Exchange Connector on an Exchange server with the Hub Transport role. Installing Exchange Connector on a separate machine to Exchange Server is also supported.

Run the installer on the appropriate servers by clicking through the wizard. There are no installation options other than the destination folder.

Exchange Connector Setup Welcome

Configuring POP3 Mailboxes

Each POP3 mailbox to retrieve messages from needs to be set up on the Mail Download tab of the Options dialog. Additionally, there are some general download options available:

  • Download interval
    This setting controls the frequency with which POP3 mailboxes are checked for new mail. When a large number of mailboxes are set up, consideration needs to be given to the increased bandwidth consumption that will result from increasing the frequency (i.e. lowering the download interval).
  • Max outbound connections
    This setting controls the maximum number of mailboxes which Exchange Connector will download from simultaneously. For a more detailed explanation of this settings, see the knowledgebase article FAQ: How does the Maximum Outbound Connections Setting work?.

Mail Download Options

Mailbox Details

When setting up POP3 mailboxes, special consideration could be given to the following settings:

  • Connect Using SSL/TLS
    If the POP3 server is external to your network and it supports SSL or TLS (encrypted communications), using SSL is strongly recommended. Without using SSL, messages and potentially passwords are sent unencrypted.
  • Disable APOP Authentication
    If you cannot successfully login to the mailbox when clicking the Test button, try selecting the Disable APOP Authentication checkbox. APOP support is an enhanced security mechanism which should be used when SSL is not used. If SSL is used, APOP is not necessary and disabling it may improve performance slightly. This setting is required in cases where a POP3 server advertises APOP support when in fact it does not support APOP or does not support it correctly.
  • Leave messages on server
    If this option is not selected, messages will be immediately deleted from the POP3 server when they have been delivered to Exchange. If Leave messages on server is selected but Delete from the server after n day(s) is not selected, messages will never be removed from the POP3 server. Leaving messages on the server should not be enabled unless specifically required, as it will increase download time, because Exchange Connector must compare the ID of each message on the server with the list of message IDs that have already been downloaded. The more messages are left on the server, the longer this operation will take.
  • Clear Download History
    If Leave messages on server is selected, Clear Download History will erase the list of message IDs Exchange Connector has retained (as a record of what has already been downloaded), and these messages will be downloaded and re-delivered to Exchange. This may result in users receiving duplicate copies of messages which have already been received.
  • Connection Timeout
    This needs to be set with consideration to the largest possible messages which may be received, and the speed of the connection to the POP3 server (especially if it is over the Internet). In most cases the default of 10 minutes is sufficient.

Mailbox Details POP3 Server


Exchange Connector can use one of two methods for determining the recipients for messages downloaded from the POP3 server:

  • Each POP3 mailbox can be assigned to one or more recipients. That is, all messages are delivered to all of these recipients. This is the recommended approach.
  • Automatic recipient detection can be enabled. It is possible to have a single mailbox on the POP3 server for all users The final recipient of each message will be determined by Exchange Connector by analyzing the message headers. This approach has advantages and disadvantages and your environment needs to be considered carefully before selecting this approach.

Automatic Recipient Selection

Automatic recipient selection reduces the administration of maintaining individual mailboxes on the POP3 server. Two significant limitations of this approach may be encountered:

  • Bcc Messages may not be able to be delivered to the correct recipient
    When automatic recipient selection is used, Exchange Connector analyses the header of the message to determine the recipient. However, if the user was Bcc'd, their email address will not be included in the email header. Most email systems work this way for security, Bcc recipients are deliberately not shown in the header. Usually in this situation, Exchange Connector will deliver the message instead to the fallback recipient, which is selected using the option If the recipient cannot be detected, deliver to this recipient. If the message contains another recipient in your organization who is not Bcc'd (they are included in the To or Cc headers), Exchange Connector will have no way of knowing that the message was also intended to be delivered to another user via Bcc, and consequently they will never receive the message.

    Some POP3 servers are able to create a Bcc header in their copy of the message to avoid the above problem. If this option is available, it should be enabled. Additionally, some POP3 servers append an additional header, such as Delivered-To, which contains the address of the intended recipient, and also allows this problem to be worked around. Custom headers can be defined by clicking the button on the Recipients tab.

    A lot of spam also contains invalid headers, or a header without the actual recipient's address. In the absence of a special header being added by the POP3 server, these messages will also be delivered to the fallback recipient.
  • Catch all mailboxes on the POP3 server increase the volume of spam received
    A feature offered by some POP3 servers is a catch all mailbox, which collects all messages sent to a specific domain. This is often used in conjunction with automatic recipient detection. However, usually this results in the POP3 server not only accepting messages from trusted addresses, such as bob@domain.com, jane@domain.com, etc. but also unwanted addresses such as xyz@domain.com which are targeted by spammers who simply try every possible combination of characters at that domain. This can dramatically increase the volume of spam received. All of these messages will be delivered to the fallback recipient, which is selected using the option If the recipient cannot be detected, deliver to this recipient.

Some additional options are available when using automatic recipient detection:

  • Also search the Received header
    For mail servers which do not support adding Bcc or other custom headers to the message, sometimes the recipient addresses can be determined by searching the Received header of the message. Unless you know the POP3 mail server supports either adding the Bcc header or another custom header, such as Delivered-To, it is strongly recommended that this option be left enabled. If the POP3 server supports adding custom headers, disabling the Received header search is recommended.
  • Also search Custom Headers & Define Custom Headers
    Additional headers can be searched to attempt to detect recipient addresses. Delivered-To for example, is supported by Gmail. If your POP3 server supports a different custom header, it can be added using the Define Custom Headers button.

Mailbox Details Recipients

Configuring Exchange Server for Message Delivery

The configuration of Exchange Server depends on the version you are using.

With all versions of Exchange, care needs to be taken that anti-spam and anti-virus filters do not block messages delivered by QSS Exchange Connector to Exchange, unless the Delete the message permanently delivery setting is used (see discussion below). Failure to observe this will lead to messages permanently remaining on the POP3 server.

In Exchange 2003, the default configuration usually works with minimal changes. In Exchange 2007 and Exchange 2010, you may need to create a new Receive Connector. In Exchange 2013, it is recommended to create a separate Receive Connector specifically for Exchange Connector.

See the knowledgebase articles for detailed instructions:

Outbound message delivery (i.e. messages sent to external recipients outside your organization) is still handled by Exchange when using our POP3 connector. A simple way to configure outbound mail is to set Exchange to forward or "smart host" the mail through another mail server, such as your ISP's mail server. Instructions are provided for this configuration for the supported versions of Exchange:

Configuring Exchange Connector Delivery Options

General delivery settings (not for a specific mailbox) are configured on the Delivery tab of the Options dialog.

Ensure that the Exchange server name and port are correctly set on the Delivery tab of the Options dialog. In Exchange 2007 and above, the port is defined in the Receive Connector in Exchange (see the knowledgebase article for instructions on configuring Receive Connectors). If Exchange Connector is not installed on the same machine as the Exchange Server messages should be delivered to, the Exchange Server name should be the fully qualified DNS name of the Exchange Server. If Exchange Connector is installed on the Exchange Server to forward messages to, the default value of localhost may be sufficient. If localhost does not work, firstly try using the fully-qualified DNS name of the server. Due do variations in DNS and IPv6 configuration, in some cases, it may be necessary to use an IP address instead of the server name. Only IPv4 IP addresses are supported.

Test the connection by clicking the Test button next to the Exchange server name on the Delivery tab of the options dialog. If an "unable to relay" error is displayed (as shown below), messages may appear to be delivered but it is highly likely that it will not work reliably and some messages may be left on the POP3 server. It is essential that the relay test is able to complete successfully.

Additional delivery options are available to determine how messages which are rejected by Exchange should be handled.

  • Send a delivery failure report to the administrator
    This is the default option and should always be used until the configuration has been fully tested. If a message is rejected by Exchange, for example, by the spam filter, it will remain on the POP3 server. Using this option, anti-spam and anti-virus filters must be disabled or bypassed for the Receive Connector which is used by Exchange Connector. This is recommended where it is possible to do filtering on the POP3 server instead (which is strongly recommended).
  • Delete the message permanently
    It cannot be stressed enough that the configuration must be tested before selecting this option to prevent messages being lost. This option is only used when anti-spam or other filtering which returns the 5550 5.7.1, 554 5.7.1 or 554 5.1.0 error codes in the SMTP session is used on the Exchange server to filter messages. Using this architecture, the original sender will not be notified that their message is rejected. In a POP3 connector environment, this is the only way to do anti-spam filtering on the Exchange server (which is why it is recommended to do it on the POP3 server instead).
  • Folder Delivery
    If you would like all messages stored in .EML format for archiving purposes in a specific folder, this option can be selected.

Delivery Options

Error Reporting / Logging Options

You can configure the administrator address to send delivery failure reports to, as well as whether Quantum Software Solutions receive error reports. It is recommended that the administrator address be a local mailbox on the Exchange server. If it is not, you need to ensure that the relay settings which are applied to SMTP connections from Exchange Connector to Exchange will allow messages to be sent to the external address. Also note that if message data is not included in delivery failure reports, these failed messages will not be deleted from the POP3 server until the delivery issue is resolved.

SQL Server logging is primarily intended for diagnostic purposes with the assistance of Quantum Software Solutions support. Note that you must set up the database before enabling SQL Server Logging. There is a SQL script installed in the installation folder which needs to be run in SQL Management Studio or similar to create the database. See the knowledgebase article for full instructions.

Error Reporting / Logging Options


If after performing the above steps messages are not delivered to Exchange recipients, see the knowledgebase article for troubleshooting instructions. For further assistance, contact Quantum Software Solutions support for further investigation. Setting up SQL logging may be of assistance. Detailed instructions can be found in this knowledgebase article.