Spam Filtering Update

We’ve had a full month of our new edge SMTP service in place now so I thought I’d do a very quick post taking a look at how well it had performed in the last four weeks. Firstly the positive:

• 190,203 (!) attempts to send messages without authenticating
• A sum total of 430,431 (!!!) attempts to brute force passwords
• 2,022 IP address automatically banned (in addition to the 213,809 we block anyway)
• The 2,022 IPs were blocked a total of 69,459 times
• 28 detected compromised accounts – this is the fewest in a month since April
• Only two compromised accounts in the last week of October – the fewest in a week since April 7th
• No new blacklistings for any any outbound mail server!
• SenderScore reputation >95% on all outbound mail servers

It’s not all positive though – there’s still some things to improve:

• Approximately 559 spam messages managed to get through the new service from about five spam attacks (this number is actually very low – we’d previously have done this in under half an hour)
• A similar number of e-mails and attacks from other non-SMTP methods
• A number of false-positive detections on accounts. We’re working on fixing these now.

The outlook (somewhat unintentional pun) is positive though. Let’s see what November brings!