We all hate the idea of doing anything that will end up making us deal with even more email than we have to manage now. But this is one of those situations where what you don't know can hurt you.

Dow Jones, like all big organizations, has been forced to subscribe to an antispam service to keep a firehouse of illicit and offensive mail messages from reaching its employees, reporters included. When the service was first turned on, Outlook inboxes were suddenly free of offers for prescription medicines, mortgage refinances, crude erotica and all the other mainstays of the spam economy. Regular email life could resume -- spam-free. It looked like another victory for technology in the hands of the good guys. If it seemed too good to be true, well, that happens all the time in the tech world.

But after a while, some of my colleagues and I began to wonder where all that spam was going, and whether there was a chance that maybe, just maybe, some of the emails being flagged as spam and sent to an email gulag were actually just innocent communications. (For the longest time, regular access to those files had been blocked by IT policy.)

I asked IT managers for access to what was being caught in our spam filters -- the messages held back in quarantine and not delivered to our inboxes. When access finally was granted to me, and others in the rank and file here, you could hear the gasps from cubicles when we all saw what we had been missing.

The antispam system had been so effective because it had labeled as spam just about everything that was even remotely suspect. It was acting a bit like a police department that, in an effort to curb juvenile delinquency, was hauling in all teenagers without 'A' averages. Naturally, a huge percentage of the emails weren't spam at all. Our freedom from spam had come at a stiff price -- a very high false-positive rate.

How bad was it?

I took a good long look at a few days' worth of messages in my spam bucket. There were 192 in all. Sorting them by hand into 'real mail' and 'actual spam,' I figured that some 46% were legitimate messages that had been flagged as spam. Of these, most were news releases from companies, including VMWare, Dell and Hewlett-Packard. Notices from Purdue University, the Semiconductor Industry Association and Forbes Magazine also were blocked, though maybe that last one wasn't such a bad call after all.

I can live without the occasional news release. But what about when real readers take the time to sit down and write to me? That's a message I want to see.

Alas, of the 150 readers to write about a recent column, 20% were sent to the spam bucket and would never have been seen by me if I hadn't bothered to ask to take a look.

Other reporters who had taken advantage of the more-open accesspolicy had similar tales. One colleague said his spam bucket contained a note from a friend he had assumed was angry with him because he hadn't written. Another found a crucial message from the company's official health-care provider announcing an important change in a health plan.

Spam researchers say this sort of thing is happening all the time at companies everywhere. 'Your experience is not at all unique,' says David Dagon, who studies spam detection at Georgia Tech. 'Antispam technology has become pretty mature in the last few years, but a lot of innovation still has to occur because the problem is so dynamic.'

The antispam software at my shop is provided by Postini, and we can assume it's at least as good as anyone else's by virtue of the fact that Google bought Postini last year.

Postini President Scott Petry seemed surprised that so much of my good mail was being flagged as spam. He said the software uses a number of different variables to score a message; those above a certain threshold get tagged as spam.

Those news releases, for example, were being sent from a single mailbox that had been configured in a way similar to the method spammers like to use. And one of the readers who had written to me had mentioned hospitals and charity work. A lot of spam involves charity scams, which is probably why that message got flagged, he said.

Mr. Petry then proceeded to explain aspects of our antispam software that I never knew about and that could be used to shrink the spam net. Specifically, Postini allows individual users to determine how aggressive its spam's filters should be. By default, our filters had been set to a vigilance level of four on a 1-to-5 setting, with five being the most exclusionary.

It turned out -- and this was news to most of us -- that the spam filter could be set by each user to be as aggressive or as permissive as each of us wished. I could lower the rating, Mr.Petry said, and start to see some of the messages that I had previously been missing.

Of course, I would also start seeing a lot more spam. And here you have the sad truth about the state of the art in spam protection. Set up your software to a low setting and you'll get most of your mail, but lots of spam. Ratchet up the controls and you'll see fewer stock picks, but you might miss the note from a long-lost friend.

Next time someone starts telling you about how smart computers have become, remind them about this situation, will you?

如果要让我们多花点时间，处理一下比现在更多的电子邮件，恐怕谁都不会喜欢这种提议。不过，在这种情况下，令你烦恼的可能恰恰是你不知道的东西。

和其他大型机构一样，道琼斯(Dow Jones)也被迫定制了反垃圾邮件服务，以阻止那些来路不明、惹人生厌的电子邮件接触到包括记者在内的员工。这一服务刚刚开通时，处方药、抵押贷款再融资、赤裸裸的色情图片以及垃圾邮件经济中的所有其他主流信息突然统统从Outlook收件箱里消失了。正常的电邮往来可以重新开始──而且见不到一封垃圾邮件。这看起来像是正义之师在科技界夺取的又一场胜利。如果这一切因为太过美好而显得难以置信的话，好啦，这是科技世界常有的事。

Michael Sloan 不过一段时间以后，我和一些同事开始盘算起那些垃圾邮件的去处，或许，仅仅是或许，某些被标记为垃圾信件并被打入万劫不复之地的电子邮件实际上只是些无毒无害的正常信息（很长一段时间以来，IT政策一直限制进入垃圾邮件文档。）

我请求IT经理允许我查看垃圾邮件过滤器里到底逮到了什么──也就是那些被隔离出来的、没有投递到收件箱的信息。我和这里的其他普通员工最终得到了允许，当我们大家看到自己究竟错过些什么消息时，格子间里传出了阵阵惊讶的声音。

这个反垃圾邮件系统之所以如此奏效，是因为它把哪怕是只有那么一丁点儿可疑的信件都划作了垃圾。这和警察局为了阻止青少年犯罪，把所有学习成绩没达到"优秀"的青少年都抓起来有点儿相似之处。显然，不少电子邮件根本不是什么垃圾。我们为摆脱垃圾邮件付出了沉重的代价──误判率非常之高。

问题到底有多严重？

我仔仔细细地查看了几天来我的垃圾邮件箱里的信件，总共有192封。我动手将这些邮件分成了"真正的邮件"和"真正的垃圾"两类。我估计大约有46%被标记为垃圾邮件的信件都是正常信息。其中大多数是包括VMWare、戴尔(Dell)和惠普(Hewlett-Packard)在内的公司发布的新闻稿。来自普渡大学(Purdue University)、半导体行业协会(Semiconductor Industry Association)和福布斯(Forbes Magazine)的通知也被阻拦，尽管福布斯的通知或许根本算不上是什么坏信息。

对我来说，偶尔的几篇新闻稿看不到倒也无所谓。但是如果真正的读者花时间坐下来给我写信怎么办？那是我想要看到的东西。

在读者对我最近一篇专栏文章寄来的150封信件中，有20%被送进了垃圾桶。如果我没有费心要求查看垃圾邮件箱的话，这些信件我根本不会看到。

那些也利用这个机会查看邮箱的记者们也有类似的经历。一个同事说，他的垃圾邮件箱里有一封朋友寄给他的信，因为一直没有收到朋友的来信，他本以为这位朋友生气了。还有个同事发现了一条重要的消息：公司医疗保健供应商宣布对医疗计划作出一项重大调整。

垃圾邮件的研究人员表示，这种事情在各个地方的公司里都是常事。Georgia Tech研究垃圾邮件检测的大卫•达贡(David Dagon)说，"你的经历根本算不上特殊。反垃圾邮件技术在过去几年已经变得十分成熟，不过仍有待创新，因为问题也十分突出。"

我电脑里安装的反垃圾邮件软件是由Postini提供的，我们可以推测它至少和其他产品一样好，因为谷歌(Google)去年收购了这家公司。

当得知我有那么多有用的邮件被标记为垃圾，Postini总裁斯科特•佩特里(Scott Petry)看起来十分惊讶。他说，该软件使用许多不同变量来为一封邮件打分；超过某一界限则被标记为垃圾邮件。

比如，那些新闻稿都是从单一的一个邮箱中发出，设置方法同垃圾邮件制造者的惯用方式相似。有个给我写信的读者提到了医院和慈善工作。许多垃圾邮件都和慈善诈骗有关，他说，或许这就是该邮件被标记出来的原因。

佩特里接下来介绍了我们使用的反垃圾软件，许多功能我毫无所知，比如我还可以设定垃圾邮件的过滤级别。Postini允许用户决定其垃圾过滤器的过滤强度。我们的过滤器在默认状态下设定在了1-5级的警戒级别，也就是4级，而5级是最具排他性的。

事实上每个用户可以按照自己的喜好设定垃圾邮件过滤器到底是百毒不侵还是相对自由──这对我们大多数人来说还是个新鲜事。佩特里说，我可以降低级别，这样就可以看到之前丢掉的那些信息了。

当然，更多的垃圾邮件也会出现在我面前。垃圾邮件防护技术发展水平的悲哀现实也就摆在了面前。设置在低级别，你会收到大部分邮件，还有许多垃圾信息。加强控制级别，垃圾是变少了，不过也可能错过久未联系的老朋友的信件。

下次有人跟你说起电脑已经变得有多么智能，别忘了提醒他们还存在这个问题，好吗？
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