I wrote a new unified IP logging/retention system, and I changed the way backups are done in order to ensure limited retention on certain privacy-sensitive things. See: https://bitcointalk.org/privacy.php

Previously I said that IPs are only logged when you post and in some limited other cases, such as when you encounter certain errors. This is no longer true: you should now think about IP logging as happening constantly.

There's now an option in your account settings which will allow you to reduce retention of your logged IPs to 3 months. You should only consider enabling this if you've staked a pubkey in the thread and you're sure that your account email is correct. I'm not sure if 3 months is enough to respond adequately to all abuse; we'll see, and I might change it later or perhaps restrict it based on rank.

I considered putting a warning on trust pages for users who have enabled limited retention, since it theoretically might make legal action against them more difficult in case they scam you, but my current thinking is that this is kind of pointless because someone could just not enable the setting and use Tor for the same effect. And it'd be both privacy-invasive and futile whack-a-mole to try to indicate when people are using proxies. On the other hand, scammers are often pretty stupid, so I could be convinced to add the warning.