unable to view postfix email from centos 7 command line, why not?

I have postfix installed on a development box and I used the parameters from this other posting to configure postfix to work on localhost only. But the other posting does not explain how to send emails or view received emails from the command line. I have higher level code for sending/receiving smtp email, but I want to be able to do it from the command line first in order to validate the postfix is working before I start testing the higher level code. I have made several tries and seem to be sending emails, but I cannot find the emails that have been sent. How can I confirm that the emails have been sent and also read the emails from the command line?

EDIT#1:

I typed MAIL=/home/root/Maildir in the terminal then hit return, then typed mail and hit return. I did this in the root account and again in the username account. This showed a list of old emails in the root account, so I logged into the username account and typed the following to send an email from username to root:

sendmail root@localhost <<EOF
subject:This is a test
from:username@localhost
Body message here...
EOF

The preceding code resulted in another command prompt with no error. But when I logged back into root and typed mail again to check mail, the new email was not listed along with the old emails.

Also, main.cf is as follows:

queue_directory = /var/spool/postfix
command_directory = /usr/sbin
daemon_directory = /usr/libexec/postfix
data_directory = /var/lib/postfix
mail_owner = postfix
myorigin = localhost
inet_interfaces = localhost
inet_protocols = all
unknown_local_recipient_reject_code = 550
mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
relayhost = 
alias_maps = hash:/etc/aliases
alias_database = hash:/etc/aliases
home_mailbox = Maildir/
mailbox_command = 
debug_peer_level = 2
debugger_command =
    PATH=/bin:/usr/bin:/usr/local/bin:/usr/X11R6/bin
    ddd $daemon_directory/$process_name $process_id & sleep 5
sendmail_path = /usr/sbin/sendmail.postfix
newaliases_path = /usr/bin/newaliases.postfix
mailq_path = /usr/bin/mailq.postfix
setgid_group = postdrop
html_directory = no
manpage_directory = /usr/share/man
sample_directory = /usr/share/doc/postfix-2.10.1/samples
readme_directory = /usr/share/doc/postfix-2.10.1/README_FILES

What am I doing wrong?

EDIT#2:

After IanMcGowan's suggestions, I checked to see that mailx was already installed. I then used this tutorial to test sending and receiving emails using the mailx commands, but I am not able to read the newly send emails either. I think it is a configuration problem. I am using email addresses like root@localhost and username@localhost.

telnet localhost 25 results in:

Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
220 localhost.localdomain ESMTP Postfix

nano /var/log/maillog contains:

Jan  5 12:09:40 localhost postfix/postfix-script[6162]: starting the Postfix mail system
Jan  5 12:09:40 localhost postfix/master[6164]: daemon started -- version 2.10.1, configuration /etc/postfix
Jan  5 12:46:00 localhost postfix/postfix-script[3036]: starting the Postfix mail system
Jan  5 12:46:00 localhost postfix/master[3047]: daemon started -- version 2.10.1, configuration /etc/postfix
Jan  5 13:12:02 localhost postfix/smtpd[4642]: connect from localhost.localdomain[127.0.0.1]
Jan  5 13:12:02 localhost postfix/smtpd[4642]: DB1249A618: client=localhost.localdomain[127.0.0.1]
Jan  5 13:12:02 localhost postfix/cleanup[4645]: DB1249A618: message-id=<1738078707.0.1420492322780.JavaMail.username@localhost.localdomain>
Jan  5 13:12:02 localhost postfix/qmgr[3058]: DB1249A618: from=<[email protected]>, size=632, nrcpt=1 (queue active)
Jan  5 13:12:02 localhost postfix/smtpd[4642]: disconnect from localhost.localdomain[127.0.0.1]
Jan  5 13:12:02 localhost postfix/local[4646]: DB1249A618: to=<[email protected]>, orig_to=<root@localhost>, relay=local, delay=0.11, delays=0.06/0.02/0/0.03, dsn=2.0.0, status=sent (delivered to maildir)
Jan  5 13:12:02 localhost postfix/qmgr[3058]: DB1249A618: removed
Jan  5 14:29:20 localhost postfix/pickup[5207]: 7F4439A616: uid=1000 from=<username>
Jan  5 14:29:20 localhost postfix/cleanup[5266]: 7F4439A616: message-id=<[email protected]>
Jan  5 14:29:20 localhost postfix/qmgr[3058]: 7F4439A616: from=<[email protected]>, size=334, nrcpt=1 (queue active)
Jan  5 14:29:20 localhost postfix/local[5271]: 7F4439A616: to=<[email protected]>, orig_to=<root@localhost>, relay=local, delay=0.13, delays=0.1/0.01/0/0.02, dsn=2.0.0, status=sent (delivered to maildir)
Jan  5 14:29:20 localhost postfix/qmgr[3058]: 7F4439A616: removed
Jan  5 14:57:10 localhost postfix/pickup[5207]: A21B49A618: uid=0 from=<root>
Jan  5 14:57:10 localhost postfix/cleanup[5529]: A21B49A618: message-id=<[email protected]>
Jan  5 14:57:10 localhost postfix/qmgr[3058]: A21B49A618: from=<[email protected]>, size=534, nrcpt=1 (queue active)
Jan  5 14:57:10 localhost postfix/local[5531]: A21B49A618: to=<[email protected]>, orig_to=<root>, relay=local, delay=0.38, delays=0.34/0.01/0/0.03, dsn=2.0.0, status=sent (delivered to maildir)
Jan  5 14:57:10 localhost postfix/qmgr[3058]: A21B49A618: removed
Jan  5 15:47:38 localhost postfix/pickup[5207]: F312D9A618: uid=0 from=<root>
Jan  5 15:47:39 localhost postfix/cleanup[5975]: F312D9A618: message-id=<[email protected]>
Jan  5 15:47:39 localhost postfix/qmgr[3058]: F312D9A618: from=<[email protected]>, size=458, nrcpt=1 (queue active)
Jan  5 15:47:39 localhost postfix/local[5977]: F312D9A618: to=<[email protected]>, orig_to=<username@localhost>, relay=local, delay=0.12, delays=0.09/0.01/0/0.03, dsn=2.0.0, status=sent (delivered to maildir)
Jan  5 15:47:39 localhost postfix/qmgr[3058]: F312D9A618: removed
Jan  5 15:48:20 localhost postfix/pickup[5207]: A826C9A618: uid=1000 from=<username>
Jan  5 15:48:20 localhost postfix/cleanup[5975]: A826C9A618: message-id=<[email protected]>
Jan  5 15:48:20 localhost postfix/qmgr[3058]: A826C9A618: from=<[email protected]>, size=461, nrcpt=1 (queue active)
Jan  5 15:48:20 localhost postfix/local[5977]: A826C9A618: to=<[email protected]>, orig_to=<username@localhost>, relay=local, delay=0.11, delays=0.08/0/0/0.03, dsn=2.0.0, status=sent (delivered to maildir)
Jan  5 15:48:20 localhost postfix/qmgr[3058]: A826C9A618: removed
Jan  5 15:48:29 localhost postfix/pickup[5207]: 54AA19A618: uid=1000 from=<username>
Jan  5 15:48:29 localhost postfix/cleanup[5975]: 54AA19A618: message-id=<[email protected]>
Jan  5 15:48:29 localhost postfix/qmgr[3058]: 54AA19A618: from=<[email protected]>, size=461, nrcpt=1 (queue active)
Jan  5 15:48:29 localhost postfix/local[5977]: 54AA19A618: to=<[email protected]>, orig_to=<root@localhost>, relay=local, delay=0.11, delays=0.09/0/0/0.02, dsn=2.0.0, status=sent (delivered to maildir)
Jan  5 15:48:29 localhost postfix/qmgr[3058]: 54AA19A618: removed
Jan  5 15:52:03 localhost postfix/pickup[5207]: C756E9A618: uid=0 from=<root>
Jan  5 15:52:03 localhost postfix/cleanup[6074]: C756E9A618: message-id=<[email protected]>
Jan  5 15:52:03 localhost postfix/qmgr[3058]: C756E9A618: from=<[email protected]>, size=491, nrcpt=1 (queue active)
Jan  5 15:52:03 localhost postfix/local[6076]: C756E9A618: to=<[email protected]>, orig_to=<root@localhost>, relay=local, delay=0.13, delays=0.09/0.01/0/0.03, dsn=2.0.0, status=sent (delivered to maildir)
Jan  5 15:52:03 localhost postfix/qmgr[3058]: C756E9A618: removed
Jan  5 16:02:36 localhost postfix/smtpd[6213]: connect from localhost.localdomain[127.0.0.1]
Jan  5 16:04:26 localhost postfix/smtpd[6213]: disconnect from localhost.localdomain[127.0.0.1]  

The logs say delivered to maildir. Am I using the wrong syntax to access maildir contents? If so, what is the correct syntax? Or is the problem in main.cf above?

EDIT#3

I typed nano /var/spool/mail/root and was able to view the old emails that show up when I log in as root and type mail or mailx. But the new emails are not located there. These emails are automated and seem to be relics from before postfix was configured to use /Maildir structure.