Hello, i've already read a lot of texts about this topic, but i've never achieved to run my server as requested. I run postfix on SUSE Linux 11. I've got several registered domains with subdomains running on my postfix. So far, i've always added a system account user for each e-mail address in my mail domain (Let's call it maindomain.com) Now we will get new customers and i want to use a completely new domain for these new customers called newdomain.com. This time, i don't want to use local system accounts for each users. I've already have enough users in my /etc/passwd. So the best solution seems to use virtual mailbox domains. I've already tried some configuration but never succeeded. Look at my main.cf: As you see, i already use the "virtual_alias_maps" for mapping real email addresses to forged addresses , because i have to separate them laterwards with a special POP3 Listener. As far as i know, i need the following settings in my main.cf (Eventually i'm wrong) : But here again, the virtual_alias_maps would use my existing virtual file and this is not what i want, as i mentioned before. The final question is: How can i add this second new domain using virtual domains and virtual users , but keeping the local domains/users and settings as they are.