I've been trying to sort this out for the past 6 hours or so, this is the error message I'm facing (Running CentOS x64):

/var/log/maillog:

Jun 22 20:42:49 ptroa postfix/smtpd[10130]: warning: SASL authentication failure: Password verification failed
Jun 22 20:42:49 ptroa postfix/smtpd[10130]: warning: bzq-79-177-192-133.red.bezeqint.net[79.177.192.133]: SASL PLAIN authentication failed: authentication failure
Jun 22 20:42:49 ptroa postfix/smtpd[10130]: warning: bzq-79-177-192-133.red.bezeqint.net[79.177.192.133]: SASL LOGIN authentication failed: authentication failure

/var/log/messages:

Jun 22 20:15:38 ptroa saslauthd[9401]: do_auth         : auth failure: [user=myuser] [service=smtp] [realm=domain.com] [mech=pam] [reason=PAM auth error]

I have dovecot installed as well and I'm able to receive emails via the MySQL authentication.

The problem is when I'm trying to use SMTP to send out emails.

Some config files:

/etc/postfix/main.cf:

# See /usr/share/postfix/main.cf.dist for a commented, more complete version

# Debian specific:  Specifying a file name will cause the first
# line of that file to be used as the name.  The Debian default
# is /etc/mailname.
myorigin = /etc/mailname

smtpd_banner = Server Message
biff = no

# appending .domain is the MUA's job.
append_dot_mydomain = no

# Uncomment the next line to generate "delayed mail" warnings
#delay_warning_time = 4h

readme_directory = /usr/share/doc/postfix

# TLS parameters
smtpd_tls_cert_file = /etc/postfix/smtpd.cert
smtpd_tls_key_file = /etc/postfix/smtpd.key
smtpd_use_tls = yes
smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache

# See /usr/share/doc/postfix/TLS_README.gz in the postfix-doc package for
# information on enabling SSL in the smtp client.

myhostname = domain.com
alias_maps = hash:/etc/aliases
alias_database = hash:/etc/aliases
myorigin = /etc/mailname
mydestination =
relayhost =
mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
mailbox_size_limit = 0
recipient_delimiter = +
inet_interfaces = all
html_directory = /usr/share/doc/postfix/html
message_size_limit = 30720000
virtual_alias_domains =
virtual_alias_maps = proxy:mysql:/etc/postfix/mysql-virtual_forwardings.cf, mysql:/etc/postfix/mysql-virtual_email2email.cf
virtual_mailbox_domains = proxy:mysql:/etc/postfix/mysql-virtual_domains.cf
virtual_mailbox_maps = proxy:mysql:/etc/postfix/mysql-virtual_mailboxes.cf
virtual_mailbox_base = /home/vmail
virtual_uid_maps = static:5000
virtual_gid_maps = static:5000
smtpd_sasl_auth_enable = yes
broken_sasl_auth_clients = yes
smtpd_sasl_authenticated_header = yes
smtpd_recipient_restrictions = permit_mynetworks, permit_sasl_authenticated, reject_unauth_destination
virtual_create_maildirsize = yes
virtual_maildir_extended = yes
proxy_read_maps = $local_recipient_maps $mydestination $virtual_alias_maps $virtual_alias_domains $virtual_mailbox_maps $virtual_mailbox_domains $relay_recipient_maps $relay_domains $canonical_maps $sender_canonical_maps $recipient_cano$
virtual_transport = dovecot
dovecot_destination_recipient_limit = 1

/etc/default/saslauthd:

START=yes
DESC="SASL Authentication Daemon"
NAME="saslauthd"
MECHANISMS="pam"
MECH_OPTIONS=""
THREADS=5
OPTIONS="-c -m /var/spool/postfix/var/run/saslauthd -r"

/etc/pam.d/smtp:

#%PAM-1.0
#auth       include     password-auth
#account    include     password-auth
auth    required   pam_mysql.so user=mail_admin passwd=password host=127.0.0.1 db=mail table=users usercolumn=email passwdcolumn=password crypt=1 verbose=1
account sufficient pam_mysql.so user=mail_admin passwd=password host=127.0.0.1 db=mail table=users usercolumn=email passwdcolumn=password crypt=1 verbose=1