It's becoming more and more of a problem all the time, to the extent that it's almost rendering Hotmail completely useless - SPAM! Right now, I am trying to use my Hotmail account for job search correspondence. And all would be well, if it wasn't for the horrendous amount of spam I receive on a daily, and now almost hourly basis. Get rich quick scams, creams to increase the size of your genitalia, liquid Viagra, get a degree by doing absolutely nothing or click here to meet single women in your area - there it all is, intermixed with legitimate mail. And there's so much of it that sorting the spam from the real stuff is just getting to be too much of a pain. Hotmail has a huge problem not just with the amount of spam sent to accounts but the amount of Hotmail accounts used to send spam!
But now, it looks like a lot of the problems with spam and Hotmail are due to a new vulnerability in the Hotmail service that allows spammers to script their spam sending.
"Hotmail has always been a problematic spam source. The saving grace has been that the spam had to be transmitted manually, through a web form, so the sending rate was limited by how fast the spammer could cut-n-paste. Now that Microsoft has provided this new programmatic interface for spammers, that limit has been removed. Spammers may now script their spam runs--and they do--which has created a huge increase in spam transmitted by Hotmail. Out of my last 25 Hotmail spams, 2 were transmitted by web form and the rest by the DAV exploit: a 2200% increase!"
More here.