Sqirrelmail, Postfix and Dovecot - postfix-mta

Question

I have installed Sqirrelmail, Postfix and Dovecot. Sqirrelmail does not relay any errors. There is no incoming or sending of mail.
Where "user1" is the user logged into Sqirrelmail.
Can anyone see my issue?
In var/log/mail.log
Jun 20 18:40:37 ip-172-31-25-194 dovecot: imap-login:
Login: user=, method=PLAIN, rip=127.0.0.1, lip=127.0.0.1, mpid=13181, secured, session=
Jun 20 18:40:37 ip-172-31-25-194 dovecot: imap(user1):
Disconnected: Logged out in=44 out=831
Jun 20 18:40:37 ip-172-31-25-194 dovecot: imap-login:
Login: user=, method=PLAIN, rip=127.0.0.1, lip=127.0.0.1, mpid=13183, secured, session=
Jun 20 18:40:37 ip-172-31-25-194 dovecot: imap(user1): Disconnected: Logged out in=285 out=1659
Jun 20 18:40:44 ip-172-31-25-194 postfix/smtpd[13184]: connect from localhost[127.0.0.1]
Jun 20 18:40:44 ip-172-31-25-194 postfix/smtpd[13184]: 6090B41CF0: client=localhost[127.0.0.1]
Jun 20 18:40:44 ip-172-31-25-194 postfix/cleanup[13187]: 6090B41CF0: message-id=<6afb833b41b27d476223ad9c04ae5a6c.squirrel#xxxxx.com>
Jun 20 18:40:44 ip-172-31-25-194 postfix/qmgr[29043]: 6090B41CF0: from=, size=699, nrcpt=1 (queue active)
Jun 20 18:40:44 ip-172-31-25-194 postfix/smtpd[13184]: disconnect from localhost[127.0.0.1]
Jun 20 18:40:44 ip-172-31-25-194 dovecot: imap-login:
Login: user=, method=PLAIN, rip=127.0.0.1, lip=127.0.0.1, mpid=13189, secured, session=
Jun 20 18:40:44 ip-172-31-25-194 dovecot: imap(user1): Disconnected: Logged out in=600 out=524
Jun 20 18:40:44 ip-172-31-25-194 dovecot: imap-login:
Login: user=, method=PLAIN, rip=127.0.0.1, lip=127.0.0.1, mpid=13191, secured, session=
Jun 20 18:40:44 ip-172-31-25-194 dovecot: imap(user1): Disconnected: Logged out in=117 out=1535

Answer 1

Update, I can now send mail to external domains, but not receive from external domains.
But user1#mydomain.com & user2#mydomain.com can send and receive emails to each other.
MX record exists:
10 # mail.mydomain.com 1 Hour
0 # smtp.mydomain.com 1 Hour
doveconf -n
auth_mechanisms = plain login
mail_location = maildir:~/Maildir
namespace inbox {
inbox = yes
location =
mailbox Drafts {
special_use = \Drafts
}
mailbox Junk {
special_use = \Junk
}
mailbox Sent {
special_use = \Sent
}
mailbox "Sent Messages" {
special_use = \Sent
}
mailbox Trash {
special_use = \Trash
}
prefix =
}
passdb {
driver = pam
}
protocols = pop3 imap
service auth {
unix_listener /var/spool/postfix/private/auth {
group = postfix
mode = 0660
user = postfix
}
}
ssl = no
userdb {
driver = passwd
}
postconf -n
alias_database = hash:/etc/aliases
alias_maps = hash:/etc/aliases
append_dot_mydomain = no
biff = no
config_directory = /etc/postfix
home_mailbox = Maildir/
inet_interfaces = all
inet_protocols = ipv4
mailbox_size_limit = 0
mydestination = mydomain.com, ip-172-31-25-194.us-west-2.compute.internal, localhost.us-west-2.compute.internal, localhost
myhostname = mydomain.com
mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
myorigin = /etc/mailname
queue_directory = /var/spool/postfix
readme_directory = no
recipient_delimiter = +
relayhost =
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache
smtpd_banner = $myhostname ESMTP $mail_name (Ubuntu)
smtpd_relay_restrictions = permit_mynetworks permit_sasl_authenticated defer_unauth_destination
smtpd_tls_cert_file = /etc/ssl/certs/ssl-cert-snakeoil.pem
smtpd_tls_key_file = /etc/ssl/private/ssl-cert-snakeoil.key
smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
smtpd_use_tls = yes