Just a quick note on how to do this:
- Decide on your username and password.
- To generate the password: sudo doveadm pw -s SHA512-CRYPT
- Copy and paste everything except what’s in the curly brackets.
- Then create a folder in /var/spool/mail/vhosts/<domain> called the same as your username.
- Create a virtual_users record in the Roundcube database using the email address and the password, not forgetting to pick the domain.