Anyone sending a lot of email has complained about spam filters and false positives at some point. But most people haven’t run a mailbox with no spam filters in front of it in recent years, so don’t have much of a feel for what an unfiltered mailbox looks like, how important filters are and how difficult their job is.

I run no transaction level filters in front of my mailbox, just content filters that route mail to one of several inboxes or a junk folder, so if I want to I can look at what unfiltered email looks like. I took data from all mail that was sent to me yesterday, and put it in a format that really shows the problem filters face and especially the difficulty of spotting which mail in the junk folder is a false positive.

An inbox with no filters looks like this.

Running a spam filter against it, simply categorizing each email as spam (pink) or not-spam (green) looks like this.

Even with the messages categorized as spam vs not-spam it’s hard to work out which messages are important and which aren’t, let alone where the false positives might be.

If I sort the categories by hand you get this – where you can see that out of 1200 or so mails about three quarters were spam. Of the three false positives two were bulk email that I didn’t care that I didn’t receive and only one was email that I considered important.

I’ll be back to posting when I get back into the office mid-May.

Aloha!

While we were cleaning up the design we also fixed some functionality that was broken and added some new features:

• Everything should render cleanly in most any browser
• Search works!
• The archives, over on the right hand side, are a lot easier to navigate
• If you visit the blog from your cellphone you’ll get a nice layout customized for the smaller screen
• Down at the bottom of each post are some little badges that’ll let you share the article via twitter or facebook or digg or …
• The little badges also let you send the article via email, or convert it to a print-friendly PDF
• There’s a live-ish feed of Laura and I on twitter on the right hand side
• If you post a comment you’ll find that we generate a little monster avatar for you, if you don’t have a gravatar set up
• Our RSS feed for new comments is a bit more visible than it was

We’ll be tweaking things over the next couple of weeks – if you see any problems comment here or email us

Tagging an email address is something the owner of an email address can do to make it easier to handle incoming email. It works by adding an extra word to the local part of the email address separated by a special character, such as “+”, “=” or “-”. So, if my email address is steve@example.com, and I’m signing up for the MAAWG mailing lists I can sign up with the email address steve+maawg@example.com. When mail is sent to steve+maawg@example.com it will be delivered to my steve@example.com mailbox, but I’ll know that it’s mail from MAAWG. I can use that tag to whitelist that mail, to filter it to it’s own mailbox and a bunch of other useful things.

In some ways this is similar to recent disposable email address services, but rather than being a third party service it’s something that’s been built in to many mailservers for well over a decade. It doesn’t require me to create each new address at a web page, instead I can make tags up on the fly. And it works at my regular mail domain.

If you’re an ESP it can be interesting to look for tagged addresses in uploaded lists. If it’s a list owned by Kraft and you see the email address steve+gevalia@example.com in the list, that’s a strong sign that that email address at least was really volunteered to the list owner. If you see the email address steve+microsoft@example.com then it’s a strong sign that it wasn’t, and you might want to look harder at where the list came from.

One reason that this is relevant to email address capture is that tagged addresses are something that you should expect people, especially more sophisticated users of email, to use to sign up to mailing lists and that they’re something you don’t want to discourage. Yet many web signup forms forbid entering email addresses with a “+” or, worse, have bugs in them that map a “+” sign in the email address to a space – leading to the signup failing at best, or the wrong email address being added to the list at worst. This really annoys people who use tagged addresses to help manage their email, and they’re often exactly the sort of tech-savvy people who make a lot of online purchases you want to have on your lists.

More on Monday.

“Successful Marketing Strategies” doesn’t just tell readers they should send relevant e-mail. It explains how to achieve relevance and measure it. It explains old-school concepts such as how to market using recency, frequency and monetary value. It explains calculating customer lifetime value and the cost to acquire a new customer, and how to use that information in easy-to-understand terms.

It also covers topics unique to e-mail marketing, such as crafting effective subject lines and harnessing the power of transactional messages.

Besides being extremely timely, “Successful Marketing Strategies” is highly readable and, most importantly, useful. And that’s the best compliment a trade book can receive.

Sounds like a book to add to my bookshelf.

I hope everyone has a happy and relaxed holiday season. I am looking forward to resting, recharging and returning ready to take on 2009.