I get a large number of quite similar emails from a particular address, most of which Outlook 2010 identifies as spam. None of these are actually spam. I have Outlook's junk email proection set to Low, and have told it to trust email from my contacts. I have added the address to my list of safe senders, and I have also tried adding it to my contacts.

However: it keeps dropping the address from my safe senders list - I add it, it stays there for a while, but eventually I'll have a legitimate mail identified as spam, and the address will have been dropped from the list. Meanwhile, despite adding that sender to my contacts, it is still classifying their mail as junk.

Any ideas of how to fix this?