在virtualmin中无法接收外部电子邮件

我已经在ubuntu服务器上安装了postfix和dovecot和webmin + virtualmin来运行邮件服务器，我按照virtualmin教程进行了设置。

但是现在我可以发送外发邮件了，但是我收不到外来的邮件！我只能收到本地用户的邮件。

知道如何解决吗？

这是postconf -n输出：

alias_database = hash:/etc/aliases
alias_maps = hash:/etc/aliases
append_dot_mydomain = no
biff = no
broken_sasl_auth_clients = no
config_directory = /etc/postfix
import_environment = MAIL_CONFIG MAIL_DEBUG MAIL_LOGTAG TZ XAUTHORITY DISPLAY LANG=C RESOLV_MULTI=on
inet_interfaces = all
inet_protocols = all
mailbox_size_limit = 0
mydestination = mail.karshenasan-nezam.com, karshenasan-nezam.com, localhost.com, , localhost
myhostname = karshenasan-nezam.com
mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
myorigin = mail.karshenasan-nezam.com
readme_directory = no
recipient_delimiter = +
relayhost =
sender_dependent_default_transport_maps = hash:/etc/postfix/dependent
smtp_tls_note_starttls_offer = yes
smtp_use_tls = yes
smtpd_banner = $myhostname ESMTP $mail_name (Ubuntu)
smtpd_client_restrictions = permit_mynetworks permit_sasl_authenticated
smtpd_sasl_auth_enable = yes
smtpd_sasl_security_options = noanonymous
smtpd_tls_auth_only = yes
smtpd_tls_cert_file = /etc/ssl/certs/ssl-cert-snakeoil.pem
smtpd_tls_key_file = /etc/ssl/private/ssl-cert-snakeoil.key
smtpd_use_tls = yes
virtual_alias_maps = hash:/etc/postfix/virtual