1. Marketing Installation and Administration Guide
  2. Bounce Handler Daemon

Bounce Handler Daemon

Typically, the Bounce Handler Daemon (BHD) receives and processes bounced mail on port 25 (the default SMTP port).

Email messages that have bounced appear similar to regular email, though their email message content and headers probably have noticeable differences in content. For a bounced email to be returned to the Bounce Handler Daemon, the original email must have a usable return address (the SMTP envelope from address). The correct SMTP envelope From Address is generated for you using the Bounce Handler Daemon's domain name (supplied by you when you configure the Email Marketing Server).

The recommended approach is to place the Bounce Handler Daemon computer in the DMZ. However, some network support technicians can choose to place the Bounce Handler Daemon behind an inbound Mail Transfer Agent. The approach that you choose depends on the configuration of your network, DMZ, existing inbound Mail Transfer Agent, and firewall. The following example describes a typical approach.

You might have a domain name of example.com and an inbound Mail Transfer Agent (in this example mail.example.com) for mail to that domain. The Mail Transfer Agent mail.example.com currently routes email successfully to computers in the internal network. It might be in the DMZ with a special hole for port 25 traffic or straddling the outer firewall with one NIC in the DMZ and the other NIC on the Internet. The Bounce Handler Daemon might be running inside the DMZ, with an internal-only hostname such as example-host.internal.example.com.

In this example, you would choose a Bounce Handler Daemon hostname such as bounces.example.com that is not already used by external DNS and then perform the following steps:

  • Configure the Bounce Handler Daemon to use this hostname.

  • Add a DNS MX record for this hostname to an internal DNS server that can be contacted by the inbound Mail Transfer Agent (mail.example.com).

  • Add this hostname to the Internet DNS servers as a hostname with an IP address for the inbound Mail Transfer Agent.

Because the Internet DNS MX records for bounce.example.com point to the inbound Mail Transfer Agent, bounced email for the Bounce Handler Daemon is sent there first. Mail.example.com must be configured to relay the mail for bounces.example.com to the Bounce Handler Daemon using the internal DNS server for the correct internal IP address.

Organizations often create IP numbers that cannot be directly reached from outside their enterprise. For example, IP numbers starting with 10.* or 192.168.* are only available inside the enterprise. Similarly, organizations often have hostnames, such as my-machine.corp.example.com, that are only visible inside the company network. If you use an IP address or hostname that is only available inside your company network for your Bounce Handler Daemon hostname, then Mail Transfer Agents outside your network cannot connect to the Bounce Handler Daemon. Therefore, the Bounce Handler Daemon server must be available, directly or indirectly, from outside your network.