Invalid Hard Bounces

What is an Invalid Hard Bounce?

When you try to send an email to an address that does not exist, the email provider will return an “Invalid Hard Bounce” response. This indicates the address is not deliverable and that future attempts to deliver email to that address will also fail.  Too many invalid hard bounces from an email marketer is indicative of poor email practices, which will harm your email sender reputation.

Unlike spam complaint rates, there is no real agreed upon industry standard rate when it comes to invalid hard bounces; the fewer the better.  At Infusionsoft, we consider anything over 1% per email provider as excessive and at risk for being contacted by the Email Compliance Team.

How Did Invalid Addresses End Up On My List?

Sending to a Cold Email List

30% of subscribers change their email address every year. If you don’t stay engaged with your subscribers, many will change their email address without you knowing. This results in old, invalid addresses on your list. Regular email sending is a great way to keep your list clean and helps prevent too many hard bounces.

If you have email addresses that have not been sent to for more than 4 months, you run the risk of sending to invalid addresses. Use caution when considering email marketing to cold contacts.

Purchased or Scraped List

Generate all email lists organically through lead collection.  Any account known to have imported a purchased or scraped list is in danger of having their account suspended.

Poor Lead Generation Practices

We’ve seen fake email addresses purposely entered into web forms to get to the promised reward like an ebook or access to exclusive information. This typically happens when the potential customer doesn’t trust the company behind the promotion.

List Bombing

List bombing happens when a web bot starts to randomly fill out all the web forms it can find with email addresses from who knows where.  Obviously this can be very destructive for email marketers for a number of reasons.

Why Invalid Hard Bounces Matter

Invalid Hard Bounces are considered a symptom of poor email collection and bad email marketing practices.  As mentioned above, too many Invalid Hard Bounces will damage your sender reputation and make it harder to deliver emails to the inbox.


If you have received an email from the Infusionsoft Compliance Team about excessive invalid hard bounces being generated by your application then please read this section carefully and enact the measures needed to reduce your hard bounce rate.

  • List hygiene
  • Audit your landing pages and check for unsecured web forms
  • Audit your lead collection process for incoming invalid email addresses and take the steps needed to promote trust and loyalty to your prospective leads
  • Review the best practices guide and make improvements where necessary
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