My good old pal Paul gave me a good tip. I'd mass-mailed a notice that I had to close an old email address because of so much spam that much of it got past two potent filtering systems! He wrote:
GMail spam filtering is the best (except for one or two expensive corporate services). Any GMail account can be told to retrieve email for your old address - just go to Cogwheel, Settings, then click the Accounts and Import tab and about 2/3rds of the way down the page, you will find a place to add an existing POP mail account. Google then checks the mail for you, filters it for spam, and puts it in your inbox (though you can always use a filter rule to forward it to another email address if you really want to). I use this with some old 20 year old email addresses, that I was about to abandon because of spam. The only snag with this is that you don't get to choose the frequency that Google checks the email - it is generally about every half hour but more frequent if that account gets a lot of mail.