I need to create email accounts for multiple domains, without having to create unix accounts for each email account. One unix account per domain name is understandable, but not for individual/each email accounts.
What do you want me to say? I’ve already told you it currently isn’t a supported configuration in Virtualmin, and you’ll have to create/manage those users yourself.
Or you can write the code to implement it in Virtualmin. There used to be support for QMail virtual users way back in the day. It’s not that hard to implement. But, virtual users are not in our near-term plans (but they probably are for Virtualmin 8, but I have no estimates about when Virtualmin 8 will arrive, at least 18 months from now seems a reasonable guess).