blog » December 6, 2006/spam killing

Hmm... I need to blog more often than just twice a month...

I run my own email server, and so I have to do my own spam filtering. My email address is everywhere, so there's plenty of spots where spammers trolling the web can pick up my address. Out of curiosity, I wanted to know how much mail is getting rejected by my filtering. So I looked through my logs, and here are some numbers for the past 10 days:

• viruses rejected by clamav: 177
• spam rejected by spamassassin: 1753
• mail sent to a nonexisting user: 1326
• (I have a catchall address, so any mail sent to any user at my domain will be delivered to me. Nonetheless, there are a few addresses that do nothing but collect spam, so I have them blacklisted.)
• (200 of those were bounces — backscatter from spammers forging my email address on their spams)
• other rejections (e.g. relaying attempts): 25

In total, for the past 10 days, my server rejected 3281 messages, while 564 messages actually made it to my mailbox. I estimate that over 4 out of 5 of the messages in my mailbox are still spam (I have yet another round of spam filtering before I actually read the messages). So probably only about 100 messages were legitimate mail in the past 10 days.

So, of the mail that tries to get sent to me, only about 3% of it is legitimate.

Since I haven't had any false positives from my spam scanning, I'll probably start lowering the threshold, and rejecting more mail.