Picture this: you wake up, check your phone, and your inbox is on fire. Hundreds or even thousands of “Confirm your subscription” and “Welcome to our newsletter!” emails are pouring in, every minute, from websites you’ve never even heard of. Important messages from your bank, your boss, or your cloud accounts are suddenly buried under a tidal wave of junk.
That’s not “normal” spam. That’s an email subscription attack.
In this post, we’ll break down what these attacks are, why they happen, and how you can protect yourself if you ever become a target.
What Is an Email Subscription Attack?
An email subscription attack (also called a “subscription bomb” or “email bombing via mailing lists”) is a type of harassment and cover-up tactic where an attacker uses your email address to sign you up for a huge number of mailing lists, newsletters, and promotional emails.
Instead of sending you one spam message directly, the attacker abuses legitimate websites’ “subscribe” and “sign up for updates” forms to flood your inbox with:
- Subscription confirmations
- “Thanks for subscribing” messages
- Marketing newsletters and promos
On the surface, it might look like random spam. Underneath, it’s often a deliberate attack with a goal: to overwhelm you and to hide important emails in the chaos.
Why Email Subscription Attacks Happen
There are three main reasons attackers use this tactic.
1. Hiding important alerts during fraud
One of the most worrying uses of subscription attacks is as a smokescreen.
While your inbox is being hammered with hundreds of newsletters, the attacker might be:
- Logging in to your bank or credit card account
- Changing your shipping address on an online store
- Resetting passwords on other accounts
Any alerts from those services (“Your email address was changed,” “New login from unknown device,” “Large withdrawal notice”) can get buried inside the flood of subscription emails. The hope is that you won’t see those critical warnings until it’s too late.
2. Harassment and intimidation
Sometimes the attack is personal.
An angry ex, a doxxer, or someone holding a grudge might launch a subscription bomb simply to make your life miserable:
- Your phone keeps buzzing with endless email notifications
- Your inbox is practically unusable for hours or days
- You waste time trying to clean it up
It’s annoying, stressful, and disruptive — which is exactly what they want.
3. General disruption and chaos
Attackers also sometimes do this:
- As a “prank”
- As retaliation (for example, after a dispute in an online community)
- To target journalists, activists, or public figures
Whatever the motivation, the impact on the victim is the same: noise, confusion, and the risk of missing something that really matters.
How Email Subscription Attacks Work (Without the Technical Jargon)
Most websites have simple forms where you can type an email address and hit “Subscribe.” Many don’t require you to be logged in, and they often don’t check if the email belongs to the person submitting it.
Attackers take advantage of that.
Instead of manually typing your email address into a few forms, they typically:
- Use automated tools or scripts to submit your email address to a large number of sites
- Target mailing lists in many industries and languages to maximize volume
- Keep the attack going for hours or days, depending on their goal
The key thing to understand: the flood of email isn’t usually coming from the attacker directly. It’s coming from legitimate services you never asked to interact with.
Why This Is More Than “Just Spam”
It’s tempting to shrug this off as an annoying spam incident, but email subscription attacks are more serious than that.
Your inbox becomes unusable
If you’re getting hundreds or thousands of messages per hour:
- You can’t easily spot the few emails that actually matter
- You might miss time-sensitive messages from your job or your bank
- Your productivity takes a big hit
Critical security alerts can be buried
If this attack is timed with a real account takeover attempt, you may miss:
- “Password reset” emails
- “Unusual login activity” alerts
- “Profile information changed” notifications
By the time the dust settles, the attacker may have changed your credentials, drained a financial account, or locked you out of important services.
Your email provider might start to choke
In extreme cases, this kind of attack can cause:
- Your mailbox to hit size limits
- Your provider to throttle or temporarily delay new messages
- Automatic spam rules to misfire because of the sudden change in volume
You might also end up on rate limits when trying to clean up, which adds to the frustration.
How To Recognize an Email Subscription Attack
Here are common signs you’re dealing with a subscription bomb and not just a bad spam day:
- A sudden, massive spike in emails within minutes or hours
- Tons of messages with subject lines like:
- “Confirm your subscription”
- “Please verify your email address”
- “Welcome to our newsletter”
- Messages from hundreds of different senders and websites
- Newsletters and offers in languages you don’t speak
- Topics you’d never sign up for (online gambling, crypto schemes, random stores overseas)
If this happens, assume it’s an attack and react quickly — especially by checking that your important accounts are still secure.
Common Myths About Email Subscription Attacks
“This means my email account was hacked”
Not necessarily.
In many cases, the attacker only needs your email address, not your password. They’re abusing public forms, not logging in as you. That said, you should still:
- Treat the attack as a warning sign
- Double-check your account security and recent activity
“If I unsubscribe from everything, it will stop”
Unsubscribing can reduce some of the leftover noise after an attack, but:
- It doesn’t stop the attacker from continuing to sign you up
- Some unsubscribe links might be malicious or used to confirm your address
Unsubscribing is a cleanup step, not a defense strategy.
“This is just random spam and not a big deal”
A one-day explosion of newsletters might be “just” harassment — or it might be timed with an actual attempt to break into your accounts.
Assume it’s serious until you’ve:
- Checked your critical accounts
- Locked down your email security
- Searched your inbox for hidden alerts
The best and most cost-effective tool you can use for this type of attack is FloodCRM. With FloodCRM, you can report the victim to up to 70,000 mailing lists.
You can access FloodCRM through both the regular web and via the Tor network.
Read our Step-By-Step Guide: How To Email Bomb, SMS Bomb, And Make Phone Call Attacks.