Just to add to Peter's comment, the one issue with links via email/newsletters is that they show up as 'direct' traffic with no referral, so they are about impossible to link back to anything w/o the utm params.
Mailchimp adds their own trackers on top of the links you insert into the newsletter, which they use for tracking open/click rates, but that's almost less interesting than the source.
Why does it matter that I have a 36% click rate on the last issue, is it good? What if instead I have 10% click rate, but 1 of those people shared it with 10k more?
I understand why in general people don't like tracking, especially here on Hacker News, but I think some of it could lead to much better outcomes for all parties involved. I wonder what other solutions there are to help piece together your audience, and their interests.
I have evidence that Google follows these links though, because if you link to a "bad" site even through a redirector, Google notices and will throw you into spam or say you're phishing, etc :-)