IT Tips and Tricks

Introduction:
I have an email server with very strong spam filtering and every now and then it does see the emails that I send from our own networks as SPAM.
In order to bypass the SPAM scanner for those networks without bypassing the virus scanning of Amavis I found these instructions in Internet at:
http://verchick.com/mecham/public_html/spam/bypassing.html#1

Allow clients on my internal network to bypass scanning by using the ‘MYNETS’ policy bank. You can use the built in ‘MYNETS’ policy bank to allow clients included in $mynetworks. Let’s assume you allow all (or most) clients on your internal network to send outbound mail through your spamfilter.
The IP addresses of these clients are included in Postfix’ $mynetworks in main.cf:
mynetworks = 127.0.0.0/8 !192.168.1.1 192.168.1.0/24
In /etc/amavis/conf.d/50-user @mynetworks determines which clients will use the ‘MYNETS’ policy bank:
@mynetworks = qw( 127.0.0.0/8 [::1] [FE80::]/10 [FEC0::]/10
!192.168.1.1 192.168.1.0/24 );

And you would configure the ‘MYNETS’ policy bank as desired:
Also added to /etc/amavis/conf.d/50-user
$policy_bank{'MYNETS'} = { # clients in @mynetworks
bypass_spam_checks_maps => [1], # don't spam-check internal mail
bypass_banned_checks_maps => [1], # don't banned-check internal mail
bypass_header_checks_maps => [1], # don't header-check internal mail
};
When using the “MYNETS’ policy bank, you must use *_send_xforward_command in master.cf which enables forwarding of the client’s IP address to amavisd-new.:
smtp-amavis unix - - n - 2 smtp
-o smtp_data_done_timeout=1200
-o smtp_send_xforward_command=yes
-o disable_dns_lookups=yes
-o max_use=20
(or)
lmtp-amavis unix - - n - 2 lmtp
-o lmtp_data_done_timeout=1200
-o lmtp_send_xforward_command=yes
-o disable_dns_lookups=yes
-o max_use=20