not sure, but since it seems to show up in several combined list, I am guessing it is a harvesting program that graps email addresses and then bundles them and sells the addresses, however the address seemed to be bundled as providers. I "googled" the one you were searching for an another that showed up in the list, both addresses showed up on TER.
probably nothing serious to worry about, just the way the internet is developing in to a market place where the only item to sell is data.
though it does bring up a couple of things.
1. your provider address should only be used for that,
2. your hobbyist address should only be used for that,
do not use your address for any other website, login etc.
IE. on address showed up on TER and a database dump from a computer board.
3. email your private address from the hobbyist address to make sure you are
not providing any additional info.
4. when you sign up for a gmail/hotmail account do not provide a 2nd account for access,
5. Google your name occasionally, even your hobby handle. Use in private browsing.
follow other recommended security issues that others have provided.