A hard bounce is an undelivered email that has been returned to the sender, usually due to the recipient’s email address being invalid. A hard bounce might occur because the email domain name no longer exists, or the recipient’s email address is not known by the email server.

When you get multiple hard bounces, it can severely damage your deliverability, as your sender identity can be flagged by email servers if they think you are sending content repeatedly to random emails. This is why it is important to regularly manage your email list, so you don’t suffer from hard bounces.

In a way, a hard bounce acts like a hard credit search when you apply for credit like a loan. As opposed to a soft bounce (or soft credit search!), a hard bounce can’t be rectified, as the email address you attempt to send an email to will never actually get there in the end, as the email address and/or the server does not exist.


How do I keep my hard bounce rate down?

There are a few ways you can actively prevent your hard bounce rate from spiking too high, such as:
  • Whenever a hard bounce occurs, delete the email address from your list immediately, so you never end up attempting to re-send emails to that inactive address again.
  • Every time you start a new email campaign, use a double opt-in for your sign-up form. A double opt-in simply ensures you receive the correct email address from everyone who joins your mailing list, as they will be required to confirm their details using a code or verification link from within the inbox of their actual email account.
  • Regularly clean your mailing list, getting rid of inactive emails whenever possible – As a guide, we recommend you give your mailing list a “deep clean” every 6-12 months, as many email users update their email address after so many months (In favour of adopting more modern email servers like Gmail).
  • Steer clear of purchasing email lists – This is not only short-cutting your way to an audience, but it is also a risky strategy, as you will never know if the emails in the list are active or just randomly generated. By the time you send out re-engagement emails, you could get hard bounce rates way above the industry average, leaving you with a bad reputation amongst multiple mail servers.
Did you know?
  • Just like with soft bounces, emails focused on deals and coupons had the lowest hard bounce rate of just 0.07%, according to a 2019 survey by Mailchimp.



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