mmNet. Now with less spam
You can’t have failed to notice the meteoric rise in spam in recent months. Many commentators characterise the fluctuations in spam rates as an arms race. Spammers come up with new techniques, the anti-spam houses respond with new rules. Just recently the spammers have started winning the race again. The worst of the new breed of spam are image-based, stock scams because they are not susceptible to most common spam-catching techniques. There has also been a rise in advertising for – ahem – ‘upsizing’ products as well as the usual pharmaceuticals.
We know that some of our customers have been struggling under the load recently, and we have been working to improve the situation. We’ve finally brought it under control, to the point where we are now seeing just one or two unwanted emails slipping through the net per day.
Here’s what we’re doing:
- We’re now checking all incoming mail against the SpamHaus SBL and XBL list, and rejecting mail from IP addresses listed in their database. Using IP blacklists can be controversial, but SpamHaus make a real effort to be fair and avoid blacklisting innocent IPs. This gets rid of about 50% of spam before it even gets near your email account.
- We’ve tweaked the SpamAssassin rules on our server so that they are now much more accurate. We’ve even managed to successfully detect image spam. We’re seeing close to zero false-positives though, so we’re not just blocking images indiscriminately.
What you should do:
- Set up a filter rule. Whenever we detect a message that we suspect is spam we mark the subject line, so that it begins: [spam?] . Most email clients will allow you to easily create a folder/mailbox called ‘spam’ and set up a rule to divert all mail marked [spam?] to that folder. You can then review the folder periodically to check that no legitimate mail has slipped in. Doing this should leave you with next to no spam in your in-box. If you’re lucky enough to have an e-mail client with Bayes spam filtering built in then it should begin locking onto the word [spam?] automatically, so you may not even need to add a rule.
- Switch off catchalls. If you are still using a catch-all email address (an address which picks up mail for unknown names at your domain) now is the time to switch it off. Spammers often just guess at the first part of email addresses, so catch-all addresses are a magnet for spam. It’s much better to bounce email to unknown addresses. That way, even if someone does spell your name wrong, they will know about it.
What if you’re still getting spam?
If you’re still receiving unmarked spam, just forward it on to: spamcop@mmnet.co.uk. We’ll take a look and see if we can tweak the rules to prevent mail like that from slipping through in the future. At the very least it will be added to our Bayes database.
What if a genuine email gets marked [spam?]
Forward it on to spamcop@mmnet.co.uk. We’ll recognise that the email has been marked incorrectly, and add it to the ‘good’ Bayes database . This will help to prevent similar mis-identification in the future.
What about viruses?
Happily the SpamHaus SBL/XBL list is catching most viruses and phishing schemes before they get near your email account. If one does slip through, the Dr Web service kicks in and isolates the email.
In the spam arms race we’ve just taken the advantage back. Hopefully our clients can breathe a sigh of relief until the spammers come up with something new. We’re also working on some black secret technology to provide the same relief to people who don’t even host their email with us. Watch this space.
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