Google Webmaster Central is going to begin emailing webmasters who have been penalized by Google again, a practice they began in 2005 then ended a few months ago.
In July Google started notifying verified site owners of their penalties via a Message Center in Google Webmaster Central, but this still did not allow for Google to contact publishers who do not use Google Webmaster Tools.
Ben D’Angelo writes on the Google Webmaster Central Blog :
While Message Center is great for verified site owners, it doesn’t allow us to notify webmasters who aren’t registered in Google’s Webmaster Tools. For this reason, we plan to resume sending emails in addition to the Message Center notifications. Please note that, as before, our emails will not include attachments. Currently, the Message Center won’t keep messages waiting if you haven’t previously registered, but we hope to add that feature in the next few months. We’ll keep you posted as things change.