Junk mail filters & Spam

Just like any filter, they are only as good as the programming/criteria they have.  If you are using junk mail filters provided by third parties, they often aren't personalized to your specific tastes.  Make sure you mark items as spam so that a proper profile of what you consider to be spam is built up.  No spam filter is perfect, especially if some miscreant comes up with a novel or semi-original method of spamming.  It is a struggle as new ways of blocking spam are implemented, those who spam come up with new ways to disguise/distribute/sneak things through.