Changing your account password 'should' have absolutely no effect on the amount of spam you receive, once your email gets into the spam circuit (from what Frank mentioned) it will just get sold, added to other spam lists. Changing your password won't make a blind bit of difference, spammers don't need your password to send you spam but you need it to collect it, changing your password will still download the spam from your inbox.
Changing your password won't stop phishing attempts either (it is just another form of spam, but attempting fraud), they don't care less what your password is they want you to go visit a site (bank, ebay, paypal, etc) and enter your password (that you just changed perhaps).
I get lots of phishing attempts for banks in the USA/UK they are just speculative and not targeted, because I have never had and account at any of the banks, they are just hoping you do and are gullible enough to visit the site.
You could use an anti-spam program there are many out there some free and they in some cases will detect the phishing attempt as spam (but they are easy to detect manually). Which ever one you choose ensure it can delete spam at the email server (ISP) so you don't have to download it completely to determine it is spam. I use a paid for program MailWasher Pro, there is a free version but it only checks one email account.
So it is either get an anti-spam program or periodically get a new email address when the spam levels get too much or choose a real spam unfriendly email address q6dn39la67 @ yourisp.com not very human friendly and only give it out to those you trust to look after it, none of which is very convenient.
