Why Blacklisting Spam May Not Work 

From CIO Support


Imagine this scenario: you’re sitting at your desk and an email pings. It’s an invite to a business conference from a name that looks familiar. Glancing over it, the email itself is innocent enough and doesn’t appear phishy; the organization putting on the conference is a legitimate industry-related business.

You delete this message and forget about it. The next day you receive another message seemingly from the same sender.

You’ve decided not to attend and don’t want to receive more of these messages – you never signed up for them in the first place. So, you quickly add the email to the blacklist on your spam protection.

What does it mean to “blacklist spam”?

Your blacklist is a set of senders/IP addresses that are blocked entirely or sent automatically to your spam folder.

The list is made up of senders the spam filter has automatically designated as “spammy” based on key characteristics, or that the user has manually added.

The sender is on your blacklist now which should solve everything, right?

The following day you receive virtually the same email.

Now you’re frustrated. Has your blacklist failed you?

Looking closer at the emails, you see that in all cases, they were sent from slightly different email addresses. Sending emails from varied IP addresses and servers is a strategy that even legitimate email marketers are using to get through spam filters. To keep up, you’d have to blacklist every version of that sender’s email!

Blacklisting spam: a losing battle

Our support team at CIO Solutions sees this scenario often. Users have an annoying sender they don’t want to receive emails from anymore. So they call or email our team to get that address blacklisted. We can do this, no problem, but it won’t solve the problem long-term.

Because of this tactic of sending emails from different IP addresses to bypass spam filters, this is going to be a recurring issue. Spending time blacklisting every version as it comes in isn’t a productive use of time for anyone.

So, what are the options for stopping pesky emails from continuing to clog up your inbox?

Alternatives to Blacklisting

  • Clicking “unsubscribe”- NOT advised

Unsubscribing may seem like the obvious answer, but it’s too risky.

If it is a malicious phishing email, clicking on any links in an email could lead to a password compromise. Even if it’s a benign sender, “unsubscribes” could still go ignored or worse, confirm that you received and engaged with the message in the first place (not great practices, but it happens).

  • Increase the spam threshold- Recommended

Increasing the spam threshold is a common and free option on many spam filters. Adjusting this sets the aggressiveness of the spam filter. The more spam-like or unreputable characteristics the email has, the more proactively it will be blocked.

Unfortunately, the downside is that you run the risk of legitimate emails getting caught more often by the spam filter. However, depending on your spam filter, you can check your lists and adjust your settings to “whitelist” or approve certain senders as needed!

Making better use of your time

Increasing the spam threshold is a broader, more proactive solution than the time-consuming, frustrating, and reactive one-by-one blacklisting method. It’s true, it means you may need to do some work to allow desired emails through. But it’s much more productive to allow the things you want vs. spending time and energy trying to keep up with blocking the things you don’t!

NOTE: CIO Solutions offers additional paid tools to help flag emails based on a threshold of legitimacy. Please reach out to explore your options if this is of interest! 

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