CRM Exchange Router and Multiple CRM environments

This is a problem I came across the other day which is a bit of a trap concidering the options in the CRM Exchange Router Installation.
The customer has 3 CRM environments Development, Test and Production. For these 3 enviroments there is only one Exchange Server. When the exchange router is linked to 1 CRM server the system functions as expected however when more than one of the CRM servers is linked the system does not automatically promote any emails and does not present any errors in the event log. All 3 CRM Environments are installed with the same Administrator account.

Issues with installing multiple CRM environments in the same domain is related to Exchange and the CRM E-mail Router. With V1.2 of Microsoft CRM we are only able to point the CRM E-mail Router at one CRM installation. It can handle multiple CRM servers, but only for the same organization. Below is the Knowlegebase article that discusses this:
"How does the Microsoft CRM Exchange E-mail Router work with multiple Microsoft CRM Server installations on one domain (861418)"
Direct Link: https://mbs.microsoft.com/knowledgebase/KBDisplay.aspx?scid=kb;en-us;861418

For testing purposes, you may want to separate production environments and test environments as much as possible to limit any effects from having a test environment being changed or go up/down during the business day.
It is possible to have two CRM implementations in the same domain for production and testing purposes but can cause issues and limitations in testing. Here are some limitations
- EULA states can only use production license for 30 days. So you would want to use Adventure Works License
- Separation between production and Dev to limit any effects caused by testing
- SQL needs own server for replication
- Exchange router only work with 1 implementation per domain