Who will help me solve the problem when setting up postfix?

Who will help me solve the problem after setting up postfix? The following figure shows the Linux Enterprise Application-Linux server application information. I recently learned how to build an enterprise mail server. It is successful to use sendmail as the mta, but an error occurs when I use postfox instead.
When the POSTFIX is used, the terminal can send successfully or accept it, but Thunderbird cannot send it, causing service errors.
Failed. The network is normal. the ip address of the local server is 172.16.0.1. The CIDR block is 172.16.0.0/16...
Let's take a look at the changes I have made !!!!

The postfix is already set as the default
[Root @ server postfix] # alternatives -- display mta | head-2
Mta-status is manual.
Link currently points to/usr/sbin/sendmail. postfix

Modify in main. cf
[Root @ server postfix] # vi main. cf
Inet_interfaces = all
Smtpd_client_restrictions = check_client_access hash:/etc/postfix/access

Modify in access
[Root @ server postfix] # tail-1 access
172.16.0.0/16 OK
[Root @ server postfix] # postmap/etc/postfix/acces

Firewall disabled for testing
[Root @ server postfix] #/etc/init. d/iptables status
Firewall is stopped.


Terminal successful
1. Send email
[Root @ server postfix] # mail root@help.com
Subject: just a test
. Cc:
Null message body; hope that's OK
2. Accept emails
[Root @ server postfix] # mail
Mail version 8.1 6/6/93. Type? For help.
"/Var/spool/mail/root": 1 message 1 new
> N 1 root@help.com Sat Dec 1 13/393 "just a test"
&
But in Thunderbird testing (local server testing), there are always prompts

In win2000, outlook testing fails.
I filtered out the port.
[Root @ server postfix] # netstat-antl | grep 25
Tcp 0 0 127.0.0.1: 25 0.0.0.0: * LISTEN