Could you please paste your Amavisd config of below setting:

$policy_bank{'MYNETS'} = {   # mail originating from @mynetworks
  originating => 1,  # is true in MYNETS by default, but let's make it explicit
  os_fingerprint_method => undef,  # don't query p0f for internal clients
  allow_disclaimers => 1, # enables disclaimer insertion if available
};

# it is up to MTA to re-route mail from authenticated roaming users or
# from internal hosts to a dedicated TCP port (such as 10026) for filtering
$interface_policy{'10026'} = 'ORIGINATING';

$policy_bank{'ORIGINATING'} = {  # mail supposedly originating from our users
  originating => 1,  # declare that mail was submitted by our smtp client
  allow_disclaimers => 1,  # enables disclaimer insertion if available
  # notify administrator of locally originating malware
  virus_admin_maps => ["root\@$mydomain"],
  spam_admin_maps  => ["root\@$mydomain"],
  warnbadhsender   => 1,
  # forward to a smtpd service providing DKIM signing service
  forward_method => 'smtp:[127.0.0.1]:10027',
  # force MTA conversion to 7-bit (e.g. before DKIM signing)
  smtpd_discard_ehlo_keywords => ['8BITMIME'],
  bypass_banned_checks_maps => [1],  # allow sending any file names and types
  terminate_dsn_on_notify_success => 0,  # don't remove NOTIFY=SUCCESS option
};
$policy_bank['MYUSERS'] =
$policy_bank{'MYUSERS'} = {
    # declare that mail was submitted by our smtp client
    originating => 1,

    # enables disclaimer insertion if available
    allow_disclaimers => 1,

    # notify administrator of locally originating malware
    virus_admin_maps => ["root\@$mydomain"],
    spam_admin_maps  => ["root\@$mydomain"],
    warnbadhsender   => 0,
    warnvirussender  => 1,
    warnspamsender   => 1,

    # forward to a smtpd service providing DKIM signing service
    #forward_method => 'smtp:[127.0.0.1]:10027',

    # force MTA conversion to 7-bit (e.g. before DKIM signing)
    smtpd_discard_ehlo_keywords => ['8BITMIME'],

    # allow sending any file names and types
       bypass_banned_checks_maps => [1],
   # don't remove NOTIFY=SUCCESS option
    terminate_dsn_on_notify_success => 0,

    # don't perform spam/header/virus check.
    #bypass_spam_checks_maps => [1],
    #bypass_header_checks_maps => [1],
    #bypass_virus_checks_maps => [1],
};