Setup mail server in Ubuntu Server 13.10

Question

For the past week I have been trying to setup a mail system capeable of understanding IMAP/s and SMTP, but after digging though like hundreds of pages, I feel like writing letters again instead of sending emails.

Here's my situation: My server is accessible though a domain (let's call it foobar.com). I want to create two addresses: admin@foobar.com and office@foobar.com, both completely seperated from each other.

However, I am completely lost at I think dovecot and postfix. I am so lost I do not even know why it's not working. (This is usually not the kind of question I ask, but for the first time in Linux I feel completely overwhelmed and have no remote idea of how to start)

Edit:// I have now finally completed the referenced wiki guide and then followed the official Dovecot Wiki, but I cannot connect via Thunderbird

This is my current dovecot.conf

protocols = imap

# It's nice to have separate log files for Dovecot. You could do this
# by changing syslog configuration also, but this is easier.
log_path = /var/log/dovecot.log
info_log_path = /var/log/dovecot-info.log

# Disable SSL for now.
ssl = no
disable_plaintext_auth = no

# We're using Maildir format
mail_location = maildir:~/Maildir

# If you're using POP3, you'll need this:
pop3_uidl_format = %g

# Authentication configuration:
auth_verbose = yes
auth_mechanisms = plain
passdb {
  driver = passwd-file
  args = /etc/dovecot/users.conf
}
userdb {
  driver = static
  args = uid=vmail gid=vmail home=/home/vmail/%u
}

The postfix config is completely default.