Overview

You use a hosted email service, like Office365, and discover that when a Member sends mail to your list, which includes members with your @domain.com address as well as members with external addresses like @yahoo.com or @att.net, only the external recipients receive the message. Testing from your ListManager server reveals that DNS is failing to resolve the domain(s) that are not receiving messages.

Prerequisites

• This Solution applies to ListManager versions 12.0 and higher - get the latest version
• ListManager is configured to use Google's DNS server (8.8.8.8)

Solution

In these cases, the solution is to implement a DNS bypass. A DNS Bypass can be used to prevent ListManager from resolving certain domains with the DNS it has been configured to use. Since the introduction of ListManager 12.0, it is recommended that ListManager be configured to use Google's DNS instead of ListManager's internal DNS. If you are experiencing DNS failures, follow the steps below to create a DNS Bypass.

1. Navigate to Utilities > Administration > Server > Server Settings > DNS Bypass
   
   
2. Click the Create New DNS Bypass button
   
   1. Domain: Enter the domain for this DNS bypass entry, e.g. example.com
   2. Hostname: Enter the hostname for the MX or NS server, e.g. mx1.example.com
   3. Type: Enter the type of DNS entry (NS or MX)
   4. Address: Enter the TCP/IP address for the NS or MX domain
   5. Click Save

After creating the DNS Bypass, mailings are delivered to internal @domain.com addresses and external addresses without issues.