Ongage Private SMTP Connector

Table of Contents:

You may want to first review the general Vendor Settings online help page, prior to following this specific vendor tutorial.

Private SMTP Introductory FAQ


  • You can connect to any one of the following On-Premise or Cloud SMTPs by using our generic Private SMTP connector.
  • Please contact your Account Manager to ask our Support to enable it for you and they will send you our Private SMTP setup documentation.

Which On Premise SMTPs /MTAs does Ongage support 

  1. PowerMTAfrom Port25 (now a Message Systems company, since Feb 2015)
  2. GreenArrow by DRH Internet
  3. MailerQ is made, maintained and supported by Copernica also the makers of SMTPeter (see our Vendor Setup Tutorials for more details about SMTPeter).
  4. MDaemon is a Microsoft-Windows-based email messaging server 

Though the above is an official list of on-premise MTAs, clients have successfully connected many other MTAs such as Postfix and other generic cloud SMTP servers to Ongage.

Ongage does not support connecting to Gmail SMTP so you will not be able to save the setting: SMTP Server:

Cloud SMTPs that can be connected to with the Ongage Private SMTP connector  

Some SMTP relays, that Ongage does not have a dedicated built-in plugin for, can be connected to Ongage, using the Ongage Private SMTP connection.

Following are are cloud SMTP relays that are verified to work with Ongage using this setup:

  1. SMTPeter: (is made, maintained and supported by Copernica also the makers of MailerQ on-premise SMTP MTA).
    1. See our ESP Setup Tutorials section for the tutorial on how to setup SMTPeter in Ongage.

Can I use my own cloud SMTP server/relay using Ongage's Private SMTP connection

  • Yes, and several of our clients are doing that. Having said that, you'll need to test, if Ongage's Private SMTP connection setup works with your cloud SMTP relay, that is something that needs to be examined on a case-by-case basis.

How to setup my Private SMTP Connection

What do I need to in order to connect to my own On Premise MTA aka Private SMTP to Ongage

  • Contact your account manager about opening a private SMTP connection.
  • Ongage support will then send you documentation regarding how to connect to your private SMTP

Credentials for Private SMTP

Below are the credentials needed for setting up your Private SMTP connection 

  • SMTP Host: Enter hostname e.g.,, or its IP address e.g., 
  • SMTP Port: The incoming port for the private SMTP should be set to 2525  or optionally you can also set port 587.
  • SMTP Username: Provided by ESP/SMTP
  • SMTP Password: Provided by ESP/SMTP
  • Authentication Type: Use one of the 3 options from the dropdown as applicable (login, plain, or CRAM-MD5).
  • Use TLS: Use "Yes" or "No" as applicable (Based on the server if they support TLC or not)

Which port should I use for connecting my Private SMTP

The incoming port for the private SMTP should be set to 2525  or optionally you can also set port 587.

If you're using PowerMTA, the configuration statement looks as following: 

smtp-port 2525
smtp-port 587

Private SMTP Technical Setup FAQ

Ways to setup bounce processing for your Private SMTP 

(info) There are 2 options for setting up bounce handling (including complaint handling) in the case of a Private SMTP connection:

  1. Setup a bounce domain as described on the ESP setup page of the private SMTP and in that case, Ongage will do the bounce processing for you.

    (info) Typically this is the faster and easier setup as it requires no API development whatsoever in order to integrate your on premise MTA into Ongage.

  2. Alternatively you can update bounces and complaints via API calls from your private SMTP back to Ongage
    1. See: POST /api/v2/contacts/change_status
      1. And use one of the parameters: "bounce" / "complaint" / "soft_bounce"

      2. If you want to associate the status changes with the campaign it happened in, it you'll need to pass the {{ocx_child_id}} passed in the X-JOB header detailed below
    2. In that case there is no need to setup the bounce domain in the ESP setup page. In order to bypass setting up the Ongage bounce domain in the ESP setup of the private SMTP, you can enter the following: bypass_bounce_domain
    3. When you choose to do that, you will need to handle the bounces on your own, and can set the Return-Path header (aka bounce header address) to whatever serves you best.

The Ongnage X-JOB Header

The following X-header (or custom header if you will) is added to the header of all email messages when sent via the Ongage a Private SMTP connector:

X-JOB: some number

Where the number value is the child campaign id {{ocx_child_id}}. This ID is needed, if you're updating bounces and complaints via the API as described above.

Default number of parallel connections Ongage uses to communicate with your SMTP server

(info) When sending messages via the Ongage PSMTP connector, by default the Ongage Platform opens 30 parallel connections.

That number can be fine-tuned according to the capacity of what your SMTP Server/MTA can handle by reaching out and working with Support to get to the optimal number of parallel connections. 

PowerMTA Log Connection Data 

PowerMTA has a configuration parameter by the name of 'log-connection'. If set to true – it logs connection data. The default value of this setting is "false", meaning that if not explicitly enabled it, it's disabled.

This command can also be used to determine how many messages are sent on each connection. You can enable connection logging using the following statement:

<source XXX> 
log-connections yes 

How to set a customer Return-path custom header


For the customers who want to manage the bounce handling on their end, and want to set their own Return-path email and domain (instead of it being based on the sending domain), they can use the Custom Header option in the Ongage Private SMTP connection screen. To do so follow the steps below.

  1. Go to the Edit screen of Private SMTP ESP connection.
  2. In the bounce setup enter: bypass_bounce_domain.
  3. In the Custom Headers, enter as the name return_path and in the value field you can add the custom return path email and domain that you'd like for your Return-path (aka bounce email address).

Note: The above setup will overwrite the default Return-path that Ongage injects for this Private ESP Connection.