Tutorials | How to trace and filter spam with a domain
What is spam?
Spam is a term used for Unsolicited Commercial Email, the electronic junk mail that fills up your inbox. Note that spam email shouldn't be mixed up with SPAM the Spiced Pork and Ham luncheon meat product. Also a distinction should be made between opt-in mailing lists that you may have signed up for and unsolicited junk.
What do you mean by tracing and filtering spam?
To send you spam, someone obviously needs to know your email address. This technique lets you find out where the spammer got your address from, and stop more arriving. Once you've been spammed once, chances are you'll get a lot more.
What is a domain name?
A domain name is normally the bit of an email address after the @ symbol, so in firstname.lastname@example.org example.com is the domain name. You will need to buy a domain name normally, the price depends on the kind; a .com/.net/.org is more expensive than a .co.uk.
The other advantage of having a domain name is a better address for your website. You can normally forward www.example.com to the (often unmemorable) web address your ISP gave you.
Do I need any special features in the domain name?
Yes. For this technique to work you'll need Catch All Mail Forwarding, which is offered by many domain registration companies. Let's assume you buy example.com. Catch all forwarding means that any email sent to an address @example.com will be sent to a default address, probably the one supplied by your ISP. So email@example.com, firstname.lastname@example.org and even email@example.com would all get forwarded to the default address.
The other thing you'll need is the ability to specify specific forwarding for addresses, so that firstname.lastname@example.org for example can go to a specified address rather than the default. The more specific addresses you can set up the more effective this will be.
These features will normally be configured in a control panel on the website you bought the domain from.
So how does it work?
Every time a website wants your email address, because you have the catch all forwarding facility, you can give every site a unique address, so you might give CTH the address email@example.com. You may find it useful to keep a note of which sites have been given which addresses to make sure you give every site a unique address.
It's worth noting that if the site is going to make your address public, like on a Message Board, you can't hold that site responsible for any spam you receive. I generally add _public in the address, so something like firstname.lastname@example.org to remind me that it is a publicly available address.
I've been spammed!
Your mail software will hopefully be able to let you look at the full SMTP headers for the message. These are a list of values that specify how the email will be handled, who it's from, who it's to, the subject and a whole lot of other stuff you don't really need to know about. It's the To: header that you need to look at, this tells you where the mail was sent to. Because everyone who mails you has a unique address for you, you should be able to see where the spammer got your address from.
So I know where the spammer got my address from, what do I do now?
Well you can complain to the site that you gave that address to, but the chances of any action being taken are slim. This is where the specific forwarding addresses come in. You can specify a different destination for the address that's being spammed and that will stop it arriving in your main account. There are many free email services you can use to set up a separate email address to use as a "spam bucket" that you simply don't check regularly. There is a risk that you will ignore some mail that was legitimate, however I wouldn't want to have anything to do with a company that gave my e-mail address to spammers.
The last thing you should ever do with spam is reply to it, or to any unsubscribe address given in the message. Doing this will confirm that your address is valid and invites more spam.
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