I have been looking at email disclaimers to differentiate between two offices which are on the same domain. Exchange 2003 does not support multiple email disclaimers natively, it might be possible to script using event sinks, here is some information about event sinks: http://support.microsoft.com/kb/317327. This will allow manipulation of messages and the methods but this would be a nightmare of a task to implement, why go through all this hassle when a third-party tool can do it for you.
I have been looking at different programs that add disclaimers and the best one I found so far is Exchange Rules; looks very simple to implement and use. The URL for Exchange Rules is http://www.codetwo.com/exchange-rules/, which installs on the backend server and is administrated centrally, it can also standardise the email signatures for your company.
You can trial it and see how it goes, it is possible to continue using the trial permanently if you are happy with a two-line advert at the bottom of the disclaimer. The added two lines read:
Disclaimer added by CodeTwo Exchange Rules
www.codetwo.com
Pictures 1 & 2 show the way the advert is displayed in HTML and Rich Text Format.
Picture 1 HTML version:
If you are happy and your company does not mind with the small advert at the bottom of the email the product can be used for free permanently. If anyone has any other solutions or products for this purpose that they have been using please leave a comment it is always interesting to see alternative solutions.