Fighting email spam isn’t just about saving time, it’s a social responsability. If you spend some time to render it useless you are helping to drop the risk vs. benefit relation for spammers and so, you are actually working to stop them.
Though I don’t make an intensive use of email —I could go a few days without checking it and the sky wouldn’t fall—, I don’t like either to spend needless time with it. I use Thunderbird and its spam filter takes care of some of the dirty job, but it still misses some, so I decided to make my incoming mail folders more Zen using some ‘this is not your room’ rules.
Thunderbird hasn’t implemented global filters (note: filter refers to the policy and rule to each condition within the filter), so the provided workaround is to use the Global Inbox, then use either filters, column sorting or searches to browse mails by account. The Global Inbox is activated at the account management, under Server settings, in the Advanced dialog. The built-in Global Inbox apparently has the annoying feature of making the already received mails in the former folders non-accessible (no wizard is offered to solve that), so you must move manually all the mails from the account folders before activating it. Don’t try to replace the Global Inbox with a redirect filter: when a mail is moved it won’t be filtered by the destination folder. I know, Thunderbird filtering is a bit clumsy. It doesn’t even allow for regular expressions, oh well…
After turning on the Global Inbox, I renamed my ‘local folders’ to ‘classified e-mails’, just for semantic aesthetics. Also I added the Account column to the view (click the rightmost square thingie with a tiny down arrow).
Next, I went to Preferences | Advanced | General, then to the configuration editor to tweak mail.adaptivefilters.junk_threshold to 30%. That’s the Bayesian junk control confidence threshold. The default 90% value is very conservative, but be careful during the next days until the junk control becomes better trained (I almost missed an administrative alert right after changing the threshold). Notice that you can set the junk control to ignore mail from your contacts list.
Classifying legitimate mails is still the best way to avoid spam’s white noise (if you are using email for business probably you should be classifying mail already). I created the folders ‘10. Work’, ‘20. Contacts’, ‘30. Whitelist’, ‘40. Other senders’, ‘50. Blog comments’, ‘60. Mailing lists’, ‘70. Newsletters’, ‘80. Archive’, ‘90. Filtered Spam’ (by Sturgeon’s Law). Numbering folders allows you to sort them, in Thunderbird by default they are alphabetical. Because I’m a retro guy, I used the old BASIC line numbering.
Now it’s time to put on the filters (they are in the Tools menu). Remember that priority matters and the filters that move mails must go after those that doesn’t.
First, I set up a filter to send work and contact mails from the address books to folders 10 and 20 and whitelisted and other known addresses to folder 30. This will ensure that I’ll always read first mails that are legitimate —well, as long as I don’t make spammer friends.
Then I wanted to backup the junk control filter with some keyword checking for things I know I’m not going to be emailed about, like Rolex watches, xx% off offers, penises and so on. These can be included in the same filter with several ‘match any of these’ rules (be sure to pick the right circle button option). Because there’s some risk of false positives, I made these mails go to folder 90 instead of to the junk folder so I can review them more easily or set up a different retention policy. Anyway, non English natives like me can safely assume that fangirls/boys aren’t going to praise our physical attributes in Anglosaxon.
Blog comments (from my Wordpress blog), mailing lists, newsletters, etc., have addresses and subjects easy to match and filter. They add a lot of bulk, so keeping them apart will make it a whole lot easier to spot junk later. Some can be directly whitelisted and classified and some you may want to run them after keyword filtering.
The last filter sent all unknown senders that were left in the inbox to folder 40 (to keep them within a closer visual space and not separated by all the sent/drafts/junk folders). Additional filters and subfolders can be added before this to organize mails that come from different accounts or use certain subjects.
Finally, I reviewed the unknown senders to put all those that I could trust into a Whitelist address book. Spam exploits Blacklist system weaknesses but can’t do much against Whitelist systems because gaining trust is something that hardly can be automated. The address books are your Whitelist system so it’s important to do frequent keeping.
