You can add per-domain AV and Spam filtering support, if you wish. Just follow the following steps:

1. Open up /usr/local/atmail/mailserver/configure
2. Find:
   

   MYSQL_DOMAINS = select Hostname from Domains where Hostname='${quote_mysql:$domain}'

3. Below this, add:
   

   MYSQL_AVCHECK = SELECT Hostname from Domains where AV='1' and Hostname='$domain'
   
   MYSQL_SPAMCHECK = SELECT Hostname from Domains where Spam='1' and Hostname='$domain'

4. Then, find this line:
   

   domainlist relay_to_domains =

5. Below this, add:
   

   domainlist sa_domains = mysql;MYSQL_SPAMCHECK
   domainlist av_domains = mysql;MYSQL_AVCHECK

6. Then, find:
   

   accept  hosts = :

7. Below this, add:
   

   warn domains = +av_domains
   set acl_m1 = 1
   
   warn domains = +sa_domains
   set acl_m2 = 1

8. Then, find:
   

   acl_check_content:

9. Below this, add:
   

   accept condition = ${if match{$acl_m1}{1}}
   accept condition = ${if match{$acl_m2}{1}}

10. Login to your MySQL
11. Add the two other columns to the Domains table:
    

    mysql> alter table Domains add Spam tinyint(1) default NULL;
    mysql> alter table Domains add AV tinyint(1) default NULL;

12. To enable filtering for a specific domain, do the following:
    

    mysql> update Domains set Spam='1' where Hostname='yourdomain.com';

    Replace yourdomain.com with your chosen domain.
    
    
13. Restart atmail:
    

    % /etc/init.d/atmailserver restart