不好意思，居然超出了单贴限制长度，配置文件不完整，这里补发一下：

# 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 = $myhostname ESMTP $mail_name (Debian/GNU)
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 = no

# TLS parameters
smtpd_tls_cert_file = /etc/ssl/certs/iRedMail_CA.pem
smtpd_tls_key_file = /etc/ssl/private/iRedMail.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.

mydomain = ifreecomm.com
myhostname = mail.ifreecomm.com
alias_maps = hash:/etc/postfix/aliases
alias_database = hash:/etc/postfix/aliases
mydestination = $myhostname, localhost, localhost.localdomain, localhost.$myhostname
relayhost =
mynetworks = 127.0.0.0/8
mailbox_command = /usr/lib/dovecot/deliver
mailbox_size_limit = 0
recipient_delimiter = +
inet_interfaces = all
myorigin = mail.ifreecomm.com
#mydomain = ifreecomm.com
inet_protocols = ipv4
mynetworks_style = subnet
smtpd_data_restrictions = reject_unauth_pipelining
smtpd_reject_unlisted_recipient = yes
smtpd_sender_restrictions = permit_mynetworks, reject_sender_login_mismatch, permit_sasl_authenticated
delay_warning_time = 0h
policy_time_limit = 3600
maximal_queue_lifetime = 1d
bounce_queue_lifetime = 1d
proxy_read_maps = $canonical_maps $lmtp_generic_maps $local_recipient_maps $mydestination $mynetworks $recipient_bcc_maps $recipient_canonical_maps $relay_domains $relay_recipient_maps $relocated_maps $sender_bcc_maps $sender_canonical_maps $smtp_generic_maps $smtpd_sender_login_maps $transport_maps $virtual_alias_domains $virtual_alias_maps $virtual_mailbox_domains $virtual_mailbox_maps
smtpd_helo_required = yes
smtpd_helo_restrictions = permit_mynetworks,permit_sasl_authenticated, check_helo_access pcre:/etc/postfix/helo_access.pcre
queue_run_delay = 300s
minimal_backoff_time = 300s
maximal_backoff_time = 4000s
enable_original_recipient = no
disable_vrfy_command = yes
home_mailbox = Maildir/
allow_min_user = no
message_size_limit = 15728640
virtual_minimum_uid = 1001
virtual_uid_maps = static:1001
virtual_gid_maps = static:1001
virtual_mailbox_base = /var/vmail
transport_maps = proxy:ldap:/etc/postfix/ldap/transport_maps_user.cf, proxy:ldap:/etc/postfix/ldap/transport_maps_domain.cf
virtual_alias_maps = proxy:ldap:/etc/postfix/ldap/virtual_alias_maps.cf, proxy:ldap:/etc/postfix/ldap/virtual_group_maps.cf, proxy:ldap:/etc/postfix/ldap/sender_login_maps.cf, proxy:ldap:/etc/postfix/ldap/catch_all_maps.cf
virtual_mailbox_domains = proxy:ldap:/etc/postfix/ldap/virtual_mailbox_domains.cf
virtual_mailbox_maps = proxy:ldap:/etc/postfix/ldap/virtual_mailbox_maps.cf
sender_bcc_maps = proxy:ldap:/etc/postfix/ldap/sender_bcc_maps_domain.cf, proxy:ldap:/etc/postfix/ldap/sender_bcc_maps_user.cf
recipient_bcc_maps = proxy:ldap:/etc/postfix/ldap/recipient_bcc_maps_domain.cf, proxy:ldap:/etc/postfix/ldap/recipient_bcc_maps_user.cf
relay_domains = $mydestination, proxy:ldap:/etc/postfix/ldap/relay_domains.cf
smtpd_sender_login_maps = proxy:ldap:/etc/postfix/ldap/sender_login_maps.cf
smtpd_reject_unlisted_sender = yes
smtpd_sasl_auth_enable = yes
smtpd_sasl_local_domain =
broken_sasl_auth_clients = yes
smtpd_sasl_security_options = noanonymous
smtpd_sasl_authenticated_header = no
smtpd_recipient_restrictions = reject_unknown_sender_domain, reject_unknown_recipient_domain, reject_non_fqdn_sender, reject_non_fqdn_recipient, reject_unlisted_recipient, check_policy_service inet:127.0.0.1:7777, permit_mynetworks, permit_sasl_authenticated, reject_unauth_destination, reject_non_fqdn_helo_hostname, reject_invalid_helo_hostname, check_policy_service inet:127.0.0.1:10031
smtpd_tls_security_level = may
smtpd_enforce_tls = no
smtpd_tls_loglevel = 0
smtpd_tls_CAfile = /etc/ssl/certs/iRedMail_CA.pem
tls_random_source = dev:/dev/urandom
tls_daemon_random_source = dev:/dev/urandom
#
# Uncomment the following line to enable policyd sender throttle.
#
#smtpd_end_of_data_restrictions = check_policy_service inet:127.0.0.1:10032
virtual_transport = dovecot
dovecot_destination_recipient_limit = 1
smtpd_sasl_type = dovecot
smtpd_sasl_path = ./dovecot-auth
content_filter = smtp-amavis:[127.0.0.1]:10024

谢谢张兄。我在这里看到了对比。
http://www.iredmail.org/admin_panel.html#screenshots

是不是有如下区别？
1、
邮件列表数量的限制.开放版的限制是多少条？每一个列表内的客户数量是否也有限制？

2、
# 控制是否允许通过 POP3 或 POP3S 从服务器接收邮件。
# 控制是否允许通过 IMAP 或 IMAPS 从服务器接收邮件。
# 控制是否允许通过 SMTP 发送邮件。
# 控制是否允许接收外部发送进来的邮件。
# 控制是否允许设置邮件转发。
# 控制是否允许通过 bcc 功能对接收和外发的邮件进行监控/备份。
# 控制是否允许自定义邮件过滤过则。