Using a local SMTP forwarder

While it is possible for your email message-generating applications to communicate directly with the SMTP listener, we strongly recommend that you set up a small, local, forward-only SMTP server or virtual machine, to fulfill the role of forwarding all messages to the SMTP injection point.

See SmartRelay overview for more details.

Contactlab can assist your IT staff in selecting and setting up a local SMTP forwarder, if required.

Advantages of a local SMTP forwarder

  • Easy access to your outbound flow

    Useful when carrying out diagnostics or urgent activities, for example:

    • If your outbound flow is compromised, you can simply turn it off while investigating

    • If an application does not work correctly, you can resolve the problem without involving Contactlab

  • Your applications do not need to handle temporary connectivity issues

    The SMTP forwarder uses its local storage and the features of SMTP to manage such situations.

  • Traffic peaks are smoothed by the SMTP forwarder

    If resource limits are reached on our side, we use SMTP 4xx temporary errors to limit your message flow.

    Your SMTP forwarder simply stores and re-sends any affected messages a little later.

  • Simplified security requirements

    Only one subsystem opens outbound SMTP connections, instead of potentially a large number of application servers.

  • Because the SMTP forwarder is effectively transparent to applications, you can easily change it, add it later, or remove it.

    In most instances, all that is needed is a change of IP address for the SMTP endpoint in your application configuration.

Disadvantages of a local SMTP forwarder

  • You need at least one additional server or virtual machine
  • You need to configure the additional machine and ensure that it is secure
    • If the machine is dedicated to the SMTP forwarder role, configuration is very simple

Next page:

Recommended settings for a local SMTP forwarder


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