Once the spam filtering software is installed and ready to run with Messaging Server, you need to specify what messages to filter. Messaging Server can be configured to filter messages by user, domain, or channel. Each of these scenarios is described in the following sections:
The expression optin means that a user, domain or channel is selected to receive mail filtering.
It may be desirable to specify filtering on a per-user basis. For example, if spam or virus filtering is offered as a premium service to ISP customers, you can specify which users receive this and which don’t. The general steps for user filtering are as follows:
Specify the user LDAP attributes that activate the spam filtering software.
Set the LDAP_OPTINX options in option.dat. Example:
LDAP_OPTIN1=SymantecAV LDAP_OPTIN2=SpamAssassin |
By default, the attributes like SymantecAV or SpamAssassin do not exist in the schema. Whatever new attributes you use, you will need to add them to your directory schema. See the appropriate Directory Server documentation for instructions.
Set filter attributes in the user entries that receive spam filtering.
The values for the filter attributes are multi-valued and depend on the server. Using the example shown in Step 1, the entries are:
SymantecAV: virus SpamAssassin: spam |
For a program like Brightmail, which can filter both viruses and spam, the valid values are spam and virus. When used as a multi-valued attribute, each value requires a separate attribute entry. For example, if the filter attribute for Brightmail was set to Brightmail, the entries are:
Brightmail: spam Brightmail: virus |
This example assumes that Brightmail is used. It also assumes that LDAP_OPTIN1 was set to Brightmail in the option.dat file. The user, Otis Fanning, has the Brightmail attribute set to spam and virus in his user entry. His mail is filtered by Brightmail for spam and viruses. 14.2.2.1 User-level Filtering Example shows the Brightmail user entry for Otis Fanning.
dn: uid=fanning,ou=people,o=sesta.com,o=ISP objectClass: person objectClass: organizationalPerson objectClass: inetOrgPerson objectClass: inetUser objectClass: ipUser objectClass: inetMailUser objectClass: inetLocalMailRecipient objectClass: nsManagedPerson objectClass: userPresenceProfile cn: Otis Fanning sn: fanning initials: OTF givenName: Otis pabURI: ldap://ldap.siroe.com:389/ou=fanning,ou=people,o=sesta.com,o=isp,o=pab mail: Otis.Fanning@sesta.com mailAlternateAddress: ofanning@sesta.com mailDeliveryOption: mailbox mailHost: manatee.siroe.com uid: fanning dataSource: iMS 5.0 @(#)ims50users.sh 1.5a 02/3/00 userPassword: password inetUserStatus: active mailUserStatus: active mailQuota: -1 mailMsgQuota: 100 Brightmail: virus Brightmail: spam |
If Symantec AntiVirus Scan Engine and SpamAssassin were used, the entry would look like this:
SymantecAV: virus SpamAssassin: spam |
See 14.3 Using Symantec Brightmail Anti-Spam, 14.4 Using SpamAssassin or 14.5 Using Symantec Anti-Virus Scanning Engine (SAVSE)
You can specify which domains receive filtering. An example of this feature would be if anti-spam or anti-virus filtering were offered as a premium service to ISP domain customers. The general steps for specifying domain filtering is as follows:
Specify the domain LDAP attributes that activates the filtering software.
Set the LDAP_DOMAIN_ATTR_OPTINX options in option.dat. Example:
LDAP_DOMAIN_ATTR_OPTIN1=SymantecAV LDAP_DOMAIN_ATTR_OPTIN2=SpamAssassin |
By default, the attributes like SymantecAV or SpamAssassin do not exist in the schema. Whatever new attributes you use, you will need to add them to your directory schema. See the appropriate Directory Server documentation for instructions.
Set filter attributes in the domain entries that receive spam filtering.
The values for the filter attributes are multi-valued and depend on the server. Using the example shown in Step 1, the entries would be as follows:
SymantecAV: virus SpamAssassin: spam |
For a program like Brightmail which can filter both viruses and spam, the valid values are spam and virus. When used as a multi-valued attribute, each value requires a separate attribute value entry. For example, if LDAP_DOMAIN_ATTR_OPTIN1 was set to Brightmail, the entries would be:
Brightmail: spam Brightmail: virus |
This example assumes that Brightmail is used. It also assumes that LDAP_DOMAIN_ATTR_OPTIN1 was set to Brightmail in the option.dat file. The Brightmail attribute is set to spam and virus in the sesta.com domain entry in the DC tree for Sun LDAP Schema 1. For Sun LDAP Schema 2 you also set Brightmail in the domain entries that receive spam filtering.
All mail sent to sesta.com is filtered for spam and viruses by Brightmail. A Domain-level Filtering Example is shown below.
dn: dc=sesta,dc=com,o=internet objectClass: domain objectClass: inetDomain objectClass: mailDomain objectClass: nsManagedDomain objectClass: icsCalendarDomain description: DC node for sesta.com hosted domain dc: sesta inetDomainBaseDN: o=sesta.com,o=isp inetDomainStatus: active mailDomainStatus: active mailDomainAllowedServiceAccess: +imap, pop3, http:* mailRoutingHosts: manatee.siroe.com preferredMailHost: manatee.siroe.com mailDomainDiskQuota: 100000000 mailDomainMsgQuota: -1 mailClientAttachmentQuota: 5 Brightmail: spam Brightmail: virus |
If Symantec AntiVirus Scan Engine and SpamAssassin were used, the entry would look similar to like this:
SymantecAV: virus SpamAssassin: spam |
See 14.3 Using Symantec Brightmail Anti-Spam, 14.4 Using SpamAssassin or 14.5 Using Symantec Anti-Virus Scanning Engine (SAVSE) for more examples and details.
Filtering by source or destination channel provides greater flexibility and granularity for spam filtering. For example, you may wish to filter in these ways:
Only messages from a specific MTA relay to a backend message store
All incoming mail from a specific MTA.
All outgoing mail from a specific MTA.
Incoming and outgoing mail from a specific MTA.
Messaging Server allows you to specify filtering by source or destination channel. The mechanism for doing this are the channel keywords described in 12.12.5 Spam Filter Keywords. The following example demonstrates how to set up channel-level filtering.
Add a rewrite rule in the imta.cnf file for all inbound SMTP servers that send messages to a backend message store host. Example:
msg_store1.siroe.com $U@msg_store1.siroe.com
Add a channel corresponding to the rewrite rule with the destinationspamfilterXoptin keyword. Example:
tcp_msg_store1 smtp subdirs 20 backoff "pt5m" "pt10" "pt30" \ "pt1h" "pt2h" "pt4h" maxjobs 1 pool IMS_POOL \ fileinto $U+$S@$D destinationspamfilter1optin spam msg_store1.siroe.com |
These examples assume a filtering program specified by the number 1. See 12.12.5 Spam Filter Keywords for the keywords available for spam filtering.
This example filters all mail for spam and viruses from an MTA relay to a backend message store called msg_store1.siroe.com
Add a rewrite rule in the imta.cnf file that sends messages to a backend message store host. Example:
msg_store1.siroe.com $U@msg_store1.siroe.com
Add a channel corresponding to that rewrite rule with the destinationspamfilterXoptin keyword. Example:
tcp_msg_store1 smtp subdirs 20 backoff "pt5m" "pt10" "pt30" "pt1h" \ "pt2h" "pt4h" maxjobs 1 pool IMS_POOL fileinto $U+$S@$D \ destinationspamfilter 1optin spam,virus msg_store1.siroe.com
Example 2. Filter for spam all incoming mail passing through your MTA (Typically, all incoming messages pass through the tcp_local channel):
tcp_local smtp mx single_sys remotehost inner switchchannel \ identnonelimited subdirs 20 maxjobs 7 pool SMTP_POOL \ maytlsserver maysaslserver saslswitchchannel tcp_auth \ sourcespamfilter1optin spam tcp-daemon
Example 3. Filter all outgoing mail to the Internet passing through your MTA. (Typically, all messages going out to the Internet pass through the tcp_local channel.)
tcp_local smtp mx single_sys remotehost inner switchchannel \ identnonelimited subdirs 20 maxjobs 7 pool SMTP_POOL \ maytlsserver maysaslserver saslswitchchannel tcp_auth \ destinationspamfilter1optin spam tcp-daemon
Example 4. Filter all incoming and outgoing mail passing through your MTA:
tcp_local smtp mx single_sys remotehost inner switchchannel \ identnonelimited subdirs 20 maxjobs 7 pool SMTP_POOL \ maytlsserver maysaslserver saslswitchchannel tcp_auth \ sourcespamfilter1optin spam destinationspamfilter1optin spam tcp-daemon
Example 5. Filter all mail destined to the local message store in a two-tiered system without using user optin:
ims-ms smtp mx single_sys remotehost inner switchchannel \ identnonelimited subdirs 20 maxjobs 7 pool SMTP_POOL \ maytlsserver maysaslserver saslswitchchannel tcp_auth \ destinationspamfilter1optin spam tcp-daemon
Example 6. Filter all incoming and outgoing mail for spam and viruses (this presumes that your software filters both spam and viruses):
tcp_local smtp mx single_sys remotehost inner switchchannel \ identnonelimited subdirs 20 maxjobs 7 pool SMTP_POOL \ maytlsserver maysaslserver saslswitchchannel tcp_auth \ destinationspamfilter1optin spam,virus sourcespamfilter1optin \spam,virus tcp-daemon