The Why and How of Black Holed Email Addresses

Email addresses can be black holed. Any email sent to those addresses are ignored. They disappear, go poof.

Save yourself a ton of spam by causing all mail sent to invalid email addresses for your domain to be black holed.

Sometimes it is desirable to send an email with a "black hole address". We will look at that idea later in this article.

There are two ways to set up email black holes.

1. A specific email address may be created and specifically assigned as a black hole.

   Typically, the email address is redirected to /dev/null instead of a regular email address. Your hosting company may have a helpful control panel that does not require you to know that specific bit of technical information.

2. All email without a valid email address can be black holed instead of bouncing. It is how we typically set up emails for our domains.

   Many email addresses may be set up for a domain. If email comes in for the domain with an address that is not set up, something has to be done with the email.

   Generally, one of three things is done:

   1. A catch-all is set up to forward all such email to a certain mailbox.

   2. The email is bounced, returned to sender as undeliverable.

   3. The email is black holed.

   A catch-all can result in a lot of spam. Sometimes spammers do what is called a dictionary attack. Spam is sent to hundreds of words @example.com addresses assuming at least one will be delivered to a mailbox.

   The bounce at first glance may seem a good idea. However, it is rare a real person will make up an address to send you an email. Bouncing spam is sent back to the sender, which might also seem a good thing, except the sender is likely to be spoofed and the email bounced to an innocent person.

   Generally, black holing invalid email addresses is a good idea. You don't see the spam sent to you and nobody gets inundated with bounces.

Sending Email From a Black Hole (Invalid) Email Address

On occasion, there are valid reasons for sending an email from a black hole email address.

1. Responding to address trolls.

   Contact forms can be used by spammers to ask a question looking for a response from you. The spammer is looking to harvest a real, live email address from the reply.

   Inane questions and statements are likely to be trolling. Usually one-liners like "Do you sell things?", "Put me on your list.", "Is it cold by you?", or another equally silly.

   Sometimes you ignore such email. But, in case it is a real person or prospective customer asking a serious question, an anonymous response can be emailed, an email with a link to a contact form that can be used instead of clicking "reply."

2. No reply desired.

   Situations may come up where sending an email to someone would be a kind gesture, reporting an error on a website, for example, yet there is a desire to remain anonymous.

It can be difficult sending anonymous emails through traditional email software.

Some email software will embed a real email address in a Received or other header line even when the From or Reply-To are spoofed. You can test this by sending an email to yourself and checking it.

When receiving the test email, view the complete headers. Some email software calls this "full" headers, some "raw" headers, or a related name. When you see complete headers, there will always be at least one Received line. If you don't see a Received header line, you're not looking at complete headers.

If your email software does in fact embed a valid email address, spammers can harvest it.

In that case, a recent addition to WebSite's Secret may be used. The software is called Anonymous Email (may need to log in first).

Even with Anonymous Email, the domain name where the email is sent from will be in the complete headers. But there should be no valid email address unless you provide it in the Anonymous Email form.

When sending anonymous email, it is wise to use a sender email address you know is black holed rather than to just make up one. Save an innocent who just might have the address you made up from being spammed or from receiving a multitude of bounces.

Black holes aren't just in outer space, anymore!

Will Bontrager