Understanding Watermarking

[Martin]

Hi,

Been away on vacation and had lots to catch up in the newsgroup. :)

Read about the new watermarking feature. If i understand this correct, 
both in- and outbound mail must pass mailscanner for this to work 
correct, right?

Since i'm currently only relaying incoming mail (not outgoing) to an 
internal exchangeserver, this won't work for me? Is this correct?

Is there any documentation to read about this feature?

Thanks in advance

/ Martin