Hard vs Soft Email Bounce and How To Avoid

Are your email campaigns not getting the desired results? Struggling with a high email bounce rate?

Let's resolve that! First an explanation, then some best practices.

So first, what's an 'email bounce'?

It's when an email you send doesn't make it to the recipient's inbox, and it gets returned to you, thus turning into a bounced email. But, not all types of bounces are the same. They can be either 'hard' or 'soft'.

A hard bounce is a big problem. It means the email can't ever reach the recipient. This usually happens when something called a ‘permanent reason’ occurs. This can mean the recipient’s email address doesn't exist anymore, the recipient’s mail server is gone, or the server can't be reached at all.

These hard bounces can really hurt your email's chance of getting through in the future, so you'll want to avoid them.

A soft bounce is not as bad. It's a temporary issue. Maybe the recipient’s mailbox is full, or their server is down temporarily, or your email message is just too big. With soft email bounces, your email might get through if you try again later.

There are also ‘pending bounces’ and ‘global bounces’, which are so rare we won’t cover them in this article.

What’s considered a high bounce rate?

Reports vary. Anything under a 2% SOFT email bounce rate, is acceptable. Anything above would be a high bounce rate. Hard bounces should be reduced to 0 if at all possible. Meaning once you’ve sent email campaigns, go through the hard-bounced accounts and either remove or unsubscribe them.

Potential problems to resolve

Email service providers

Alright, so the first thing that can really cause a high email bounce rate is your 'email service provider'. This is the company that gives you the tools to send out your emails.

But remember, there's also an email service provider on the other end, for the person who's receiving your email. Both of these can have a big impact on whether you get a hard or soft bounce.

Let's start with your email service provider. If it doesn't have a good reputation, it can lead to a lot of hard bounces. See, other servers might block emails from providers that are known to send spam or unwanted content. It's like getting blacklisted at a club; once you're on the list, you're not getting in. That's a hard bounce right there.

Also, your email service provider needs to have good email deliverability rates. If it doesn't, you could end up with soft bounces. Maybe the server is too busy, or there are too many emails being sent at once. It's like trying to squeeze through a crowded bar. You might get through eventually, but it's going to take a while and you’ll probably spill your drink.

Now, on the receiving end, your receiver’s email service providers matter too. Some are super strict and might block your emails if they think they're spam, or if your provider isn't on their 'approved' list. Again, this leads to a high email bounce rate, especially hard bounces.

Hard bounces are generally the result of ‘permanent reasons’. This includes an invalid email address that no longer exists or a protection service that returns your email for example. When this happens, it’s best to just remove the invalid email address.

So you need to choose a reputable service provider for sending your emails. Do your homework. Look at their deliverability rates, their reputation, and their policies on handling bounces. A good provider will help you manage your mailing list and avoid both hard and soft bounces.

On the receiving end, it's a bit trickier. You can't control which email service provider your recipient uses. But, you can make sure your emails look legit.

More about the email itself below, first a quick section on the spam filters.

Avoiding the spam filter

Spam filters are like bouncers at a club. They decide who gets into the recipient’s inbox and who gets turned away. They're looking for signs of spam, things that make an email look suspicious. The email service provider we just talked about is one.

Another big trigger is 'spammy' language. This is stuff like "FREE!!!", "BUY NOW!!!", or "CLICK HERE!!!". Basically, anything that sounds too salesy or too good to be true can set off alarm bells.

This goes for both email content and the subject line. So keep your language clear and professional, and avoid sounding like a late-night infomercial.

The format of your email matters too. If your email is one big image, or if it has a bunch of different fonts and colors, it might look like spam. Keep your emails clean and simple to avoid this.

Spam filters also look at how many people are opening your emails and how many are marking them as spam. If lots of people are marking your emails as spam, or if very few are opening them, the filter might start blocking your emails. So, keep your emails relevant and engaging to avoid this.

The email itself

Another big part of reducing a high bounce rate is the email itself. So, let's chat about some best practices that can make a big difference.

  1. The first thing is the subject line. This is like the front door to your email. If it looks sketchy or spammy, your email might get bounced right away. That's a hard bounce waiting to happen.

So, make your subject line clear and related to your content. And avoid ALL CAPS and too many exclamation points!!! Those are big red flags for spam filters.

  1. Next, let's talk about the content of your email. One best practice here is to make sure your email isn't too heavy. If your email is jam-packed with large images or attachments, it can end up being a soft bounce. Think of it like trying to shove a giant couch through a small doorway. It just ain't gonna fit. So, keep your emails light and easy to load.
  2. Your email should also be easy to read and understand. Avoid complex jargon or industry lingo. Keep it simple and clear. If your recipient doesn't understand your email, or if it seems too complicated, it might end up in the spam folder.
  3. Another best practice is to always include a clear 'unsubscribe' link. If people can't easily unsubscribe, they might mark your email as spam. And if that happens too often, your emails will start bouncing. It's better to let people opt out if they want to.
  4. Finally, be consistent with your sending frequency. If you send too many emails, or if you send them at weird times, it can look suspicious. Stick to a regular schedule, and don't bombard your recipients with too many emails.

Your mailing list

The quality of your mailing list, a key aspect of successful email campaigns, can have a significant impact on both hard and soft bounces. So, let's break it down.

Firstly, it's important to maintain list hygiene to avoid a high bounce rate. Outdated or invalid email addresses can lead to many hard bounce email issues. After deploying your email campaigns, just go through the hard-bounced section and discard the invalid email addresses.

Remove any emails that have HARD bounced, and always verify new addresses are correct before adding them to your recipient’s email server list. You can use the Plunk Email Validator tool to check any email address.

Next, let's talk about how you're adding people to your mailing list. You want to ensure that everyone on your mailing list wants to be there, a best practice for reducing the chances of hitting the recipient’s spam folder.

This is where 'opt-in' comes in. By having people opt-in to your emails, you're ensuring they want to receive your content. This makes sure all the people on your mailing list are verified email addresses, reducing the likelihood of hard bounces.

But what about those soft bounces? If an email address constantly results in a soft email bounce, it might be worth removing it from your list. It's like trying to chat with someone who always leaves you on read. After a while, you just stop trying.

Finally, consider segmenting your mailing list. This means splitting it up into smaller groups based on things like location, interests, or open rates. By tailoring your emails to each segment, you can improve engagement and reduce the chance of both hard and soft bounces.

So, when it comes to your mailing list, keep it clean, opt in, and don't be afraid to remove addresses that aren't working.


Now you understand there are two types of bounces - hard and soft.

Hard bounces, sometimes a result of invalid email addresses or recipient’s mail server issues, are like a closed door; your emails can't get in due to a permanent reason.

Soft bounces are like knocking on a door that's temporarily stuck, your emails might get in if you knock again later.

To fix this, you've got to maintain good relationships with those who control the email world, the email service providers. Make sure your service provider is reliable, has a clean record, and doesn't risk your emails being directed to the recipient’s spam folder. And remember, the intended recipient on the other end (your reader) also has an email service provider, who might be extra picky.

Do you remember how some emails end up in the spam folder? The spam filters are always on the lookout for any red flags like spammy language or suspicious-looking emails.

But it's not just about avoiding spam filters, it's also about crafting the right email message. A catchy subject line, clear content, and avoiding jargon are the best ways to ensure your message isn't mistaken for spam. Just write like you would to a friend.

And don't forget your mailing list. It's a good idea to keep it clean, updated and ensure everyone there wants to hear from you. Take a close look at those invalid email addresses that bounce back often and consider if they're worth keeping around.

By following these best practices, you should be able to maintain a low bounce rate and high deliverability rates for your future email marketing campaigns!

Carlo D'Agnolo
CarloFounder & Head of Growth at Plunk