How to find bank employee's position with name and email only

It's difficult. If you have a friend in the same company, you can ask - typically firms have address books that list division/position. This is most accurate. Once in a while (like 1% of the time) people can connect work email to Google+. To find this out would be as easy as just entering the address in the Contact section of Gmail. Again - extremely rare, more common with VCs and consultants than with anybody else. But may be worth a try.

Google works once in a while, if the guy is senior at has spoken at some conference. Organizations he may be on the board of could list what group he works for.

On LinkedIn, it often lists "People also viewed..." - if they are all in one group, most likely your guy is in there also. You could also get some color from what industry the guy lists.

If he's not on Google and not on LinkedIn, try https://connect.data.com/ It primarily lists names and emails only, but if you're lucky it'll have what group he's with as well.

If none of those work...sorry. You should just ask him directly. Say you want to learn about the firm, not some specific area. Worst case scenario you can ask for a referral to the group you're really interested in.