Well, yeah, you make a fair point. Your correspondence isn't being datamined, but it may "leak" information to an analytics provider in indirect ways (e.g. outgoing links - just an example, I'm not sure). IN regards to Flash, though, it's not always practical to fully block it, but apart from a good dose of AdBlock and NoScript, you should also take a look at the suggestions in this Wikipedia article for dealing with other Flash-based privacy concerns.