Email and Spam Filtering

Have you ever signed up for an online service and suddenly started experiencing a surge of spammy marketing emails? The kinds of emails that are sent directly to you as part of a “customer retention” program after you buy an item like airline tickets, the ones that keep sending you emails about limited-time offers and credit card deals long after your purchase is complete?  Here I’ll discuss some strategies to deal with under-the-radar spam.

Some of those can be solved by opting out at checkout (if you can find the button) or unsubscribing, but that doesn’t prevent them from selling your email address to 3rd parties.

If you want to take control, you can employ one of the following strategies, which vary in degree of difficulty and amount of work required to set up: using Mailinator (easiest), Gmail plus-sign filtering, to setting up your own mail server. It all depends on how much control and privacy you want.

The easiest solution: just make up a address (e.g. and that mailbox is automatically and temporarily created on their server ( as soon as it receives an email – no registration necessary. Then just visit and enter the made-up email address and like magic you have mail. You never have to register, you never have to remember a password, but there’s one catch: every mailbox is public, so be careful what you sign up for.

So if you need to register for some website (e.g. to comment on a blog), register using a made-up address (e.g. Then just visit and enter “” and follow the account-activation links.

This is a disposable and public email service. Obviously, you don’t want to use a mailinator address for signing up for a bank account or buying airline tickets because everyone can see it (again, there is no login, no passwords), but for one-time disposable accounts, this the easiest, fastest solution.

To reiterate, be careful using this service as all mail is publicly available to everyone.

Gmail Filtering with the + symbol

If you are using Gmail, you can add a + sign after your name, and then filter mail that comes to that address. For example, if you are signing up for some online service hypothetically called which requires your email address, just put something easily identifiable as your email address. If your email address is, use Any time you receive an email addressed to you know for sure that whoever sent you the email got/bought it from

Now that you know who sold your email address blacklist all email that is addressed to In Gmail you can create a filter (go to Settings->Filter->Create new filter). In the to field, enter “”, click next and select “Delete it”. You can do other types of filtering, like moving to different folders too.

I used this approach for years and it has served me quite well for deleting and sorting all my mail. If anyone asked me my email address in a store (e.g. RadioShack), they would get Maybe I do want their flyers, but don’t want it to show up on my phone every day — easy, just filter it, “mark as read” and move to another folder.

The downside is that some advertisers are getting wise to this and are dropping the + sign before selling your info. Another downside is that Google still has access to your email, which means they can (and do) read your email to send you more “targeted” ads.

Your Own Server

This is the most flexible solution. If you have your own mail server, you can set a “default” email address. A default email address is a catch-all for any email account that does not exist on your system — mail sent to a non-existent email account automatically gets forwarded to the default account. In my RadioShack example, I would simply give out and it would show up in my own inbox.

And if someone sells my info I have the smoking gun: the to field gives it away. So then, simply blacklist that email address in your server settings and return to sender. Or if you would like to save those emails for the future, just create that actual account, and save the emails.

The disadvantage to this approach is that someone who knows my scheme could spam anything — this would probably work for a little while until I make tweaks to my spam software, or even temporarily turn off the feature.

Choose the right approach

Mailinator is an excellent service, but only if you need to use it for one-time signups, or throwaway accounts. Gmail filtering is awesome and versatile, but your email address may still be exposed in addition to Google looking through your emails. Setting up your own server is a little overly complicated, but provides the greatest flexibility.

Personally, I use all three approaches when the situation calls for it, although lately I am weening myself off Gmail in favor of using my own server.

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