Multiple disclaimers may be added to messages in complex infrastructures

Symptoms

Multiple disclaimers can be added to messages that route via several mailbox servers that have Exclaimer installed upon them if the message triggers a rule on each of the servers.

Cause

Exclaimer will add the disclaimer to a message if it matches a rule. On a single mailbox server, this results in just one disclaimer being added, however on multiple mailbox servers, there can be several disclaimers added because the rules match on each server.

Resolution

There are 2 ways to deal with this situation:
The first is to use the "Dont add disclaimer if the body contains" feature which is available on every disclaimer panel, and prevents the disclaimer from being added if the message already contains some string. You can provide some unique piece of information from the disclaimer such as your company number or name, or you can include a unique code - a disclaimer revision code if you like - that identifies the disclaimer has already been added.

The second, which is only suitable for use in Exclaimer 4.x series is to take advantage of one of the internet headers that Exclaimer adds to internal prevent the re-addition of disclaimers.
Use your normal default rule or custom rule to add the internal disclaimer, then create another custom rule with:

• Sender = Anyone internal
• Recipient = Message Header Equals
• In the value box, you can set this to
• X-*: Internal
• In the Disclaimer tab, you set the Disclaimer drop down to "Don't add disclaimer.".

More Information

There is a header X-[MD5-HASH-OF-MACHINE-ID] that is added by Exclaimer when an internal disclaimer is added to a message and is used to prevent the message from being processed on the same server again. This information can be used to help exclude the second disclaimer.
Since we can't know all the MD5 hashes that Exclaimer could use in a particular environment, it's unsafe to hardcode this string of hexadecimal digits. We therefore use a wildcard on the left hand side of the header test, and the right hand side is set to the value "Internal".
Since the header field cannot be entered by a user, there is no risk that they could inadvertantly get into this situation. The only risk with this is that some other X- header could have the value "Internal" but we feel this is unlikely in an internal email environment.