I don't use Spami, but doesn't it have any learning function that if you continually flag it as spam it will eventually pick them up on its own.
I have MailWasher Pro and it has heuristics, learning and Origins of spam, that really take care of most of my spam and I only have 4 filters to catch anything else.
1. MeMe - email sent to my (Me) email address purporting to come from Me, so that if flagged for deletion.
2. Not For Me - If the my email/name isn't in the To or CC address it is flagged for deletion, much of the spam you get is bulk spam and your email may not be directly addressed to you.
3. General 1 - Common words used in S P A M but not words that may easily be in normal email - like viagra, cialis, pharmacy, medicines, etc.
4. General 2 - Overflow for general 1 as there is only room for 10 rules (each with its own word).
I try to avoid adding an email address to a blacklist as they are contain moving targets as they are frequently forged, soon the blacklist is huge and may slow the receipt of email. My Blacklist currently has 0 entries.