I'm planning to run a dedicated hardware for a single domain, using ISPconfig 3. This domain will hold about 300 users and they will communicate via both POP/SMTP and IMAP for their mails. I want my users to log-in without using the full e-mail address as their user name. For example; I have a user named "adrian", if she would like to log-in to check her mails, she needs to use "firstname.lastname@example.org" as her user name. I want her to type just "adrian". As I'll be using Roundcube for the webmail, I know how to configure roundcube to disregard the domain name. But I do not know how that works for POP&SMTP. Pointers would be appreciated.