Blocking is futile.
Blocking email by the “From:” address is useless in the war against spam.
It promises to prevent email from a specific sender from reaching you, but if the sender is determined, the block is easily bypassed. And spammers are determined … boy, are they determined!
I’ll explain why blocking is pointless, and what I do instead.
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Blocking is futile
Trying to stop spam by blocking the sender is futile because spammers keep changing who the email appears to be from. The better approach is to mark spam as spam when it appears in your inbox. If it’s showing up in your spam folder, the system is already working properly.
Blocking versus the spam folder
You said the email is coming “repeatedly to my junk email box”.
That is the system working exactly as intended: spam should show up in your spam or junk folder rather than in your inbox.
In fact, depending on your email program or interface, that may be exactly what “blocking” means: “When an email from this sender arrives, put it in the junk folder.”
If this is the case, there’s nothing to fix because nothing is broken.
Misleading email addresses
Spammers work hard to mislead you. One technique — “From: spoofing” — makes emails appear as if they’re from someone they’re not.
Email addresses have two parts: the email address itself and an optional “display name”. For example, you might see:
From: Leo A. Notenboom <firstname.lastname@example.org>
The display name is “Leo A. Notenboom” and the email address is email@example.com.
The display name is optional. When present, many email programs will display it in place of the email address. Your email program might show something like:
From: Leo A. Notenboom
Spammers use this to mislead you. For example:
From: firstname.lastname@example.org <email@example.com>
Here, the display name — not the email address — is “firstname.lastname@example.org”. The actual email address is “email@example.com”. So, in some email programs, you would only see this:
It looks like an email from firstname.lastname@example.org, but it’s not — it’s really from email@example.com.
You can block “firstname.lastname@example.org” if you like, but it won’t block this particular email because that’s not where it came from.
Ever-changing email addresses
There’s another technique spammers use that renders individual address blocking completely ineffective.
They don’t send email from the same address more than once.
You might get the exact same spam over and over, but each time it’ll be “From:” a different email address. You can block that address if you like, but it won’t stop the next email they send, or the one after that, or the one after that . . . because they all come from different email addresses.
Combined with the tricks spammers use to mislead you about what email address is really being used, things get confusing very quickly.
The short answer is that using Block the Sender to stop spam is a complete waste of time and effort.
If the email arrives in your spam/junk folder already, ignore it. The system is working.
If the message arrives in your inbox, mark it as spam or junk.
Marking it as spam will move the message from your inbox to the junk folder, but it also allows the service to learn what is and isn’t spam. As you report more and more spam over time, more of it will get blocked: the software will send it to your spam folder instead of your inbox.
Gmail’s spam filter seems to be particularly effective.
If that doesn’t work, I suggest you relax and use your Delete key. It’s simple, quick, and 100% accurate.
Showing up in the spam folder is the right thing
I need to reiterate that email arriving in your spam folder is exactly what should happen if that email is spam. Yes, there might be a lot (I get hundreds a day), but that’s the system working exactly as it should.
Trying to prevent the email from reaching you at all — meaning that it never shows up in your email account’s inbox, spam folder, or any other folder ever — is pointless. Spam exists, and currently there’s no way to stop it.1
The best you and your email service can do is deal with it after it arrives.
For your email service, that means analyzing and sending spam to your spam folder. For you, that means marking spam as spam when it shows up in your inbox, and occasionally marking legitimate email that shows up in your spam folder as “not spam”.
Is blocking good for anything?
For example, if there’s a specific individual you want to block, you can block their email address.
But as I mentioned earlier, even then, blocking will be ineffective if they are sufficiently motivated to get through. All they need to do is get a new email address to send from, and those are easy to get.
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Footnotes & References
1: So called “Challenge/response” services are not a viable option, in my opinion.