User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US; rv:1.9) Gecko/2008052906 Firefox/3.0 Build Identifier: This information might be useful I strongly suspect that bugzilla email addresses have been harvested. This because I was using (until a few minutes ago) a specific email for bugzilla email@example.com. Never had spam for years until a few months ago when it started to grow. Reproducible: Always Steps to Reproduce: 1. 2. 3.
This is a known problem, see bug 261326 and it's dependencies. You're even warned when creating an account; see the right side of https://bugzilla.mozilla.org/createaccount.cgi . I'm just going to mark this INVALID, because there's no actionable information here. You can check out the bugs linked to from bug 261326 for further information on measures being considered to prevent this.