Добрый день!
При отправке письма, к примеру, с Гугл, яндекс и вообще любого почтового сервиса - письмо не приходит.

main.cf

# Directories
queue_directory         = /var/spool/postfix
command_directory       = /usr/sbin
daemon_directory        = /usr/libexec/postfix
data_directory          = /var/lib/postfix

mydomain                = example.com
myhostname              = mail.example.com

#mynetworks             = 127.0.0.1/32, 52.189.12.0/24
mynetworks              = 127.0.0.1/32, 52.189.12.184
myorigin                = $mydomain
#mydestination          = $mydomain, localhost.$mydomain, localhost.$mydomain
mydestination           = localhost,localhost.localdomain,mail.example.com,example.com
# soft_bounce           = yes
mail_owner              = postfix
inet_interfaces         = all
disable_vrfy_command    = yes
disable_dns_lookups     = no
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-2.5.6/samples
readme_director         = /usr/share/doc/postfix-2.5.6/README_FILES
inet_protocols          = ipv4
alias_maps              = mysql:/etc/postfix/sqlite-aliases.cf
alias_database          = hash:/etc/aliases
# header_checks         = regexp:/etc/postfix/header_checks
smtp_helo_name          = $myhostname
# smtpd_banner          = $myhostname ESMTP $mail_name (Bu-Ga-Ga)
#local_recipient_maps   =
unknown_local_recipient_reject_code = 550

# Relay
relay_domains           = mail.example.com
relayhost               =
#relayhost              = example.com
# relay_recipient_maps  = hash:/etc/postfix/relay_recipients

# Debug
debug_peer_level        = 3
# debug_peer_list       = 127.0.0.1
# debug_peer_list       = example.com
debugger_command        =
         PATH=/bin:/usr/bin:/usr/local/bin:/usr/X11R6/bin
         ddd $daemon_directory/$process_name $process_id & sleep 5

# Virtual domains
virtual_alias_maps      = mysql:/etc/postfix/sqlite-aliases.cf
virtual_mailbox_domains = example.com
# local_recipient_maps  = $virtual_mailbox_maps
# relay_recipient_maps  = $virtual_mailbox_maps
local_recipient_maps    =
relay_recipient_maps    =

# Transports
#local_transport        = virtual
local_transport         = cyrus
mailbox_transport       = cyrus
relay_transport         = cyrus
virtual_transport       = cyrus

# mailbox_transport     = lmtp:unix:/var/lib/imap/socket/lmtp
# virtual_transport     = lmtp:unix:/var/lib/imap/socket/lmtp
#relay_transport                = smtp
# mailbox_transport     = hash:/etc/mail/transport
# virtual_transport     = hash:/etc/mail/transport

# Rules
#smtpd_recipient_restrictions = check_relay_domains
smtpd_recipient_restrictions =
    permit_sasl_authenticated
    reject_unauth_destination
    permit_mynetworks

# SASL
smtpd_sasl_type                 = cyrus
#smtpd_sasl_path                = smtpd

smtpd_sasl_application_name = smtpd

smtpd_sasl_auth_enable          = yes
smtpd_sasl2_auth_enable         = yes
smtpd_sasl_security_options     = noanonymous
#smtpd_sasl_local_domain        = $myhostname
smtpd_sasl_local_domain         =
broken_sasl_auth_clients        = yes

smtpd.conf

#pwcheck_method: saslauthd
#mech_list: plain login

#pwcheck_method: saslauthd
#mech_list: plain login

#sasl_pwcheck_method: auxprop
#sasl_auxprop_plugin: sasldb
#sasl_mech_list: PLAIN LOGIN
log_level: 3
pwcheck_method: sasldb2
mech_list: PLAIN LOGIN CRAM-MD5 DIGEST-MD5
auxprop_plugin: sasldb
#saslauthd_path: /var/spool/postfix/var/run/saslauthd/mux
#pwcheck_method: auxprop
#auxprop_plugin: sasldb
#mech_list: PLAIN LOGIN

imapd.conf

configdirectory: /var/lib/imap
partition-default: /var/spool/imap
admins: cyrus
autocreatequota: 10000
createonpost: false
allowplaintext: yes
sievedir: /var/lib/imap/sieve
sendmail: /usr/sbin/sendmail
hashimapspool: true
sasl_pwcheck_method: auxprop
sasl_auxprop_plugin: sasldb
sasl_mech_list: LOGIN PLAIN CRAM-MD5 DIGEST-MD5
tls_cert_file: /var/imap/cyrus.crt
tls_key_file: /var/imap/cyrus.key
tls_ca_file: /var/imap/cyrus.crt
unixhierarchysep: yes
autocreateinboxfolders: spam
autosubscribeinboxfolders: spam
#allowplaintext: yes
anysievefolder: yes
altnamespace: 1
#defaultdomain: example.com
#servername: example.com
virtdomains: yes

Лог, который показывает во время попытки принять почту

Jan 16 11:02:12 localhost imap[2063]: open: user user_test@emample.com opened Infected Items
Jan 16 11:02:12 localhost squatter[1343]: indexing mailbox user/user_test@emample.com...
Jan 16 11:02:12 localhost imap[2063]: open: user user_test@emample.com opened Junk
Jan 16 11:02:12 localhost squatter[1343]: indexing mailbox user/user_test@emample.com...
Jan 16 11:02:13 localhost imap[2063]: open: user user_test@emample.com opened test
Jan 16 11:02:15 localhost master[23757]: exiting on SIGTERM/SIGINT
Jan 16 11:02:21 localhost cvt_cyrusdb[2800]: skiplist: checkpointed /var/lib/imap/deliver.db.skiplist (6211 records, 792344 bytes) in 1 second