OK, I expect to get some spam with my email account because I use it to register with many internet forums.
But the thing is, I also check on my partners email account (a work one) which is registered with mine, for our Online Trading Account with NAB, and which never gets spammed. Except for the last 2 weeks which has been flooded with share market spam emails (from the US I presume - I never open them). My partner's email account has never been used to log into any internet forum, so the only way it could get spammed with emails specifically addressed to him, and with share related information is if our Online Trading account provider has given my partners email address to others! He has had no other spam emails other than share stuff!
I cant explain it any other way. His address simply isnt out there on the web!