postfix - SquirrelMail inbox blank, emails not being stored correctly

I'm trying to set up a mail server on an Amazon EC2 Micro instance - following this post by flurdy. I've installed Postfix, Courier IMAP and Squirrel Mail. I've been testing the ability to send and receive emails via postfix - and this is working fine. I've connected to SquirrelMail succesfully - however the inbox is blank.

It appears the email files are being created at /var/spool/mail/myuser as opposed to /var/spool/mail/virtual/myuser. At first I couldn't connect to SquirrelMail - because the myuser directory wasn't initiated within virtual/. So I manually added this via

maildirmake myuser

The issue now is that the emails are not being stored within /var/spool/mail/virtual/myuser directory, but still in /var/spool/mail/myuser file.

Edit > postconf -n

alias_database = hash:/etc/postfix/aliases
alias_maps = hash:/etc/postfix/aliases
append_dot_mydomain = no
biff = no
config_directory = /etc/postfix
delay_warning_time = 4h
disable_vrfy_command = yes
inet_interfaces = all

local_recipient_maps =
mailbox_size_limit = 0
maximal_backoff_time = 8000s
maximal_queue_lifetime = 7d
minimal_backoff_time = 1000s
mydestination = $mydomain, $myhostname, localhost, localhost.localdomain
mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
mynetworks_style = host
myorigin = mymailexample.co.uk
readme_directory = no

recipient_delimiter = +
relayhost =
smtp_helo_timeout = 60s
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache
smtpd_banner = $myhostname ESMTP $mail_name (Ubuntu)
smtpd_client_restrictions = reject_rbl_client sbl.spamhaus.org, reject_rbl_client blackholes.easynet.nl, reject_rbl_client dnsbl.njabl.org
smtpd_data_restrictions = reject_unauth_pipelining
smtpd_delay_reject = yes
smtpd_hard_error_limit = 12
smtpd_helo_required = yes

smtpd_helo_restrictions = permit_mynetworks, warn_if_reject reject_non_fqdn_hostname, reject_invalid_hostname, permit
smtpd_recipient_limit = 16
smtpd_recipient_restrictions = reject_unauth_pipelining, permit_mynetworks, reject_non_fqdn_recipient, reject_unknown_recipient_domain, reject_unauth_destination, permit
smtpd_sender_restrictions = permit_mynetworks, warn_if_reject reject_non_fqdn_sender, reject_unknown_sender_domain, reject_unauth_pipelining, permit
smtpd_soft_error_limit = 3
smtpd_tls_cert_file = /etc/ssl/certs/ssl-cert-snakeoil.pem
smtpd_tls_key_file = /etc/ssl/private/ssl-cert-snakeoil.key
smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
smtpd_use_tls = yes
unknown_local_recipient_reject_code = 450

virtual_alias_maps = mysql:/etc/postfix/mysql_alias.cf
virtual_gid_maps = static:5000
virtual_mailbox_base = /var/spool/mail/virtual
virtual_mailbox_domains = mysql:/etc/postfix/mysql_domains.cf
virtual_mailbox_maps = mysql:/etc/postfix/mysql_mailbox.cf
virtual_uid_maps = static:5000

Edit>
This is the result of the concat(home,'/',maildir) from the SQL query - You can see the mail directory ends with a slash /

/var/spool/mail/virtual/myuser/             

Solved>
I noticed in the mail.log there was the following>

postfix/trivial-rewrite[16423]: warning: do not list domain mymailexample.co.uk in BOTH mydestination and virtual_mailbox_domains

..
postfix/virtual[17251]: 149535DC7: to=, relay=virtual, delay=0.14, delays=0.12/0.01/0/0.01, dsn=2.0.0, status=sent (delivered to mailbox)

I updated /etc/postfix/main.cf to

mydestination = mail.mymailexample.co.uk, localhost, localhost.localdomain

And it worked. Warning disappears and the logs now reveal (delivered to maildir)

..
postfix/virtual[17251]: 149535DC7: to=, relay=virtual, delay=0.14, delays=0.12/0.01/0/0.01, dsn=2.0.0, status=sent (delivered to maildir)