ACE is being replaced by DCS which is integration into Symantecs DLP product (formerly Vontu) for classification, it can do some very clever classification of emails. They can be based on almost anything so creating classifications based on author like requested above is simple. Based on the classification you can choose to do a number of things (delete item, apply specific retention category, apply specific CA tag etc).
Until then your best bet would be to use custom filtering to apply a different retention category to exclude from the CA searches. Your active sampling will still include some of these results because it samples all all of a users email to be compliant, even if its a newsletter. Excluding emails from sampling is technically possible if you do a hard delete of the items at the journal level using custom filtering, but you are not compliant if you do that!
Hope that helps.
