Hard Bounces: The Brick Walls Of Failure

We’ve talked a lot about email bounces and email bounce rates as a whole in the past before, but we’ve really only ever dipped our toes into the different types of bounces — hard bounces and soft bounces. Why is that? Well, they’re the smaller components that makeup more complex deliverability issues. A cog in the wheel, a fruit in the basket, a piece of the pie, or whatever other metaphor floats your boat.

Get it?

Thankfully, there isn’t any harm in defining them. For the sake of keeping this short and sweet, let’s talk about the most straightforward of the two bounce types: hard bounces.

Hard Bounces are a hard stop

Hard bounces mean that a message cannot be delivered due to an unchanging, permanent reason. There is nothing you can do to fix it, it just isn’t happening. Some examples of hard bounces are non-existent addresses, invalid domain names, the recipient’s mail server doesn’t exist, etc. As all of these examples suggest, delivery isn’t possible because there isn’t anything to deliver to in the first place.

What can they do to your email deliverability?

That depends on your ESP’s hard bounce policy. For example, here at Mailgun, we stop attempting delivery after the first send. Considering they are a hard stop when it comes to your sending, most email service providers (ESPs) will stop attempting delivery after the first attempt. No point in running into a wall over and over again, right?

Why stop sending if they don’t exist?

Because it would hurt your sender reputation if we did! Sending to an email that doesn’t exist to Gmail tells them that you might not be a legitimate sender, and in turn, makes you look like a spammer. Whether you’re seeing a lot of hard bounces with a triggered transactional email campaign or in your latest email marketing campaign, it’s best to cut them out entirely.

To accomplish this, all you have to do is clean those bad addresses from your email list. List hygiene can be accomplished with just about any email validations service, but we’re quite partial to ours (plus, it just got a major facelift — win).