the gentoo virtual users/postfix/mysql howto - help please?

[wonderboy]

i got everything installed, but i dont know how to add domains/emails to the database, if anyone has like a script for this, or an explaination for the schema that would be greatly apreciated.

[tumbak]

thats exactly where im stuck too, if i figure it out i'll surely post the info
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less QQ more pewpew!

[Oopsz]

domains go in the transport table, with local: for local user delivery and virtual: for vmail delivery. email users go in the users table. email field is the full address, clear is password, name is plaintext name (ostensibly for finger), id and gid are the numeric ids for mail delivery (use the vmail uid and gid for virtual delivery), home dir is the home dir (/home/vmail for virtual delivery), maildir is the maildir for delivery (/home/vmail/domain.ext/user/.maildir/ for virtual delivery, /home/user/.maildir/ for local delivery). quota is optional, postfix is y.
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Pop-before-SMTP with the Gentoo Virtual Mailhosting Guide

[SilverOne]

several follow-up questions:

1. In the how-to why is the virtual-mailbox-domains not read from the mysql database but from file?

2. use case:
imagine me being a hosting provider adding a new client, with the following details:
domain: seconddomain.tld
mailboxes: 5
aliases: yes
shell-user: yes (user with linux shell login and user@primarydomain.tld email address)

how do I add this to the setup as developed with the how-to?
I think it's like this:
- put 'seconddomain.tld' in the transport table (with 'destination=virtual')
- add mailuser1 through 5 to users (these users do not 'exist' in the linux passwd file) with uid/gid vmail, homedir->vmail, maildir->vmail/1-5
- add the aliases (to the virtual mailboxes) to the 'virtual' table. but what do I fill in as 'destination' in the 'virtual' table?
- the shell user, do I put that user in 'users' table? Or is that handled by the local_recipients_maps?

3. in order to be able to use a "catchall" alias, which would need to be put in 'virtual', I need to also alias each user to itself?
(I got this tip from here)
Unless I want to NOT see 'mailuser1' as an alias?
I guess I'm asking here: what does postfix do with the destination in the virtual table? Does it look up the destination in the virtual table again? (to permit daisy-chained aliases) or not. In the former case the alias mailuser1@seconddomain.tld must exist, does it not?

4. quota's are supposed to be entered in bytes?

some of the answers I think/seem to already know, but any clarification very much appreciated!