How can I have accounts with the same username/password in different domains?
If you try to create a second Account with the same username/password combination on a second domain Merak Mail Server may return an error.
There are two possible solutions:
1. Use the Login With Email Address option
When this option is enabled, all users on the server are forced to use the whole email address as their username so Merak Mail Server can recognize which domain the user belongs to.
The option is in the Domains & Accounts -> Policies -> Login Policy tab. Select the Users login with their email addresses option.

Now you can create accounts with the same user/password in any domain.
2. Use Domain IP Binding
This feature allows you to bind each domain to a particular IP address and Merak can authenticate the user according to the IP that the User is trying to access.
This is not a recommended solution as the IP Binding can cause confusion and issues.
To Bind a Domain to an IP go to domain settings and choose the Options tab.

Click the Virtual IP Binding button and enter the IP address to that you wish this domain to be bound to.
Warning - If you bind one domain to an IP address you must bind all your domains to different IP addresses.