Hello Zhang,

I've solved like this:

1) I created the file /etc/amavisd/whitelist
where I inserted the addresses of the senders that I wanted to whitelist, one per line.
it works also for whole domains (but without the @)
Example:

user1@example.com
user2@example.org
example.net
example.eu

2) in /etc/amavisd/amavisd.conf I decommented AND modified the following section:

# This policy will perform virus checks only.
read_hash(\%whitelist_sender, '/etc/amavisd/whitelist');
@whitelist_sender_maps = (\%whitelist_sender);

$interface_policy{'10026'} = 'VIRUSONLY';
$policy_bank{'VIRUSONLY'} = { # mail from the pickup daemon
    bypass_spam_checks_maps   => ['@whitelist_sender_maps'],  # don't spam-check this mail
    bypass_banned_checks_maps => ['@whitelist_sender_maps'],  # don't banned-check this mail
    bypass_header_checks_maps => ['@whitelist_sender_maps'],  # don't header-check this mail
};

Checked the logs and the headers of the messages... it works perfectly!
The messages are with no score, have the WHITELISTED tag, and get checked for virus. Exactly what I wanted.
Delivery time lowered for the whitelisted addresses from 2500-3000ms to roughly 150ms.

If you want to make this method a quick "How-To" in your doc repository, feel free to use it.

Which system are you using?
Could you post the exact error?

The only thing that comes to my mind is to verify if your whitelist file is correctly written.

Maybe you have some invisible characters or some incorrect charset (it depends by which editor you used to write your file)?
Or maybe the last line of your text file is not terminated with a newline? This happens pretty often...

try to delete your whitelist file, rewrite it with an editor like vim or nano and restart amavisd.

Let me know

Happy to have been useful, you're welcome

Looking further into it, it looks as though I can do it with soft-blacklisting.  Just give the sender a nice high score.