By some accounts, more than 90% of the mail sent on networks today is
unwanted spam. My own personal experience is that more than 99% of
the messages to me are unwanted. Of course, I have had the same email
address for 18 years, and that makes the problem worse.
On other pages of this site we have discussed programs for reading email and services and tools for generating messages that appear in your inbox. For those of you that get too much mail, you will need tools to weed out the unwanted messages that you never requested to begin with. On this page we discuss various techniques for filtering your email.
Mail Service Provided Spam FilteringMost mail hosting services today provide tools to remove unwanted email, e.g. spam and viruses, from your inbox. All too often, the tools provided by your ISP will filter more than just spam, causing you to lose messages you want. I have run mailing lists were users sign up and then complain when they don't get the mail they requested, and often it is because of problems with their spam filters, or worse, those of the internet service provider. I have seen these problems with SBCGlobal, and AOL, as well as other services.
One of the most effective mail services that I have seen in terms of its spam filtering is GMail. In fact, I have a couple of mailboxes on other services that were old addresses and which get very little legitimate mail, and I forward those message to gmail so that the few legitimate message I get pop out through the spam, with the other mail on those addresses being filtered out.
Your Corporate Mail FiltersMost companies today apply some form of spam filtering on incomming email, in a way similar to that provided by ISPs. Our company uses Spam Assassin which flags messages it thinks are spam. I have filter rules for processing my mailbox which look for these flags and moves the message to a separate mailbox, which I delete about once a month. Note that it is important to do screeing on the server, otherwise, when you connect to your mail server, lots of time is spent downloading spam, which is then deleted locally. If you are coming in over a slow connection, it really slows things down if you have to download 100 messages for every one that has real content.
Your Mail Reader - a second line of defenseIf you mail hosting service supports download of your email using POP or IMAP, then you may get a second line of defense on spam filtering. For my work address, the one that gets the most spam, messages that make it through our companies spam filters are downloaded into Thunderbird, where a second set of spam filters is applied, screening the remaining spam that made it though out company filter. Unfortunately, this line of spam filtering suffers from false positives, and on occasion I have to look throgh the filtered spam messages to see what might have been inadvertantly blocked. When I find such a message I flag it, allowing the spam filters to learn, but the apporach is not fool proof. When scanning this filtered mail I usually sorty by subject so that I can readuly skip over large chunks of correcly eliminated messages.
Other mail reading programs, such as Outlook, offer similar functionality.