Signup form subscription bombing is worth avoiding

Signup form subscription bombing is worth avoiding

Subscription Bombing

Everyone who sends email even close to properly has a sign-up form, therefore, you should have all heard about subscription bombing by now and signup form subscription bombing is worth avoiding.

Just in case you haven’t, its when a spider, bot, virus etc. finds a form on a page and submits it, a lot. Like a ddos attack but with email addresses. Thousands an hour or even a minute, relentlessly.

I’ve recently been tracking hits on a form (which is protected), for about a month, that began in China before going to the Philippines, then Hong Kong and then back from the Philippines. Mainly using numbers at qq and repeating combinations of a short list of names for other fields.

Consequences of subscription bombing on your list

There are a few consequences for a list:

  • It fills up really quick and with rubbish.
  • You can’t send to it.
  • It’s a nightmare to clean.
  • If you have a welcome message and no double opt-in, you then send dozens of thousands of┬áthose that will never be opened.
  • If you have a double opt-in email, you’ll send dozens of thousands of them but at least only the humans will confirm.

This all sounds inconvenient, expensive and very complicated to recover from…

It then gets worse when Spamhaus blocklists your IP for not sufficiently protecting your sign-up form. Apparently you should know about this and want to protect it. Also your ISP probably has a Spamhaus listing in their Ts & Cs of things not to have so now your entire hosting package is on the line.

How does Spamhaus manage to find out? interesting question, however, it matters not; it’ll make you fix it quicker and you won’t do it again.


Spamhaus is the worst blocklist to be on and most people who get on a list, deserve to be there. It’s successful, popular and reliable for a reason. But sometimes, you’re unlucky. Ignorance is not an excuse, although it may be a reason but ignorance is cured by knowledge. Sometimes you can get punished twice, when the guilt and the consequences of the first problem, what you thought was the big problem is sinking in, you get called an idiot and kicked while you are down; Signup form subscription bombing is worth avoiding. Do your home work, otherwise you look lazy and contemptuous and that never goes down well.

How to avoid subscription bombing

Double-Opt-in and reCaptcha.

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