When was the last time you checked your email bounce rate? I’m always surprised by the amount of companies I interact with who don’t monitor this metric regularly…
I know it’s an easy stat to overlook, especially when the open, click and conversion rates are the attention grabbing ones you often get asked about. But a high bounce rate can quietly chip away at your sender reputation, affecting deliverability across the board.
So, what exactly are email bounces, why do they happen and what’s the difference between a soft bounce and a hard bounce?
Let’s break it down.
First up: what is an email bounce?
An email bounce happens when your email can’t be delivered to a subscriber’s inbox and is returned (or “bounced”) back by the receiving server.
There are two types:
Hard bounce = permanent failure
This happens when the address is invalid or no longer exists. For example, a typo like emma@gmial.com or a work address that’s been removed after someone leaves a company.
These should be automatically suppressed by your ESP after the first bounce and you’ll see the bounce on the campaign report for which it occurred.
Soft bounce = temporary failure
Soft bounces usually mean the address is valid, but something temporarily blocked the delivery – think full inbox, server downtime, or message too large.
If the same address soft bounces multiple times (usually 3-5), most platforms will then suppress it automatically. On some platforms you can adjust the number of bounces you want to allow before the address is removed.
Why bounce rates matter more than you think
It’s not just about whether that one email landed or not.
High bounce rates can signal poor data quality, dodgy acquisition sources or infrequent list cleaning and Inbox providers (e.g. Gmail, Apple, Yahoo) take notice. If they detect consistent issues, it can affect where (or if) your emails land in future.
Pro tip 💡: As a general rule, aim to keep your bounce rate under 1%. If you’re hitting 2% or above, that’s a warning sign.
How to monitor email bounce data
Most ESPs will break bounce data down by:
- Hard vs soft
- Domain (e.g. Gmail, Yahoo, Hotmail)
- Individual addresses
- Send type (campaign vs automation)
Keep an eye on your overall average and whether certain domains, campaigns or automations are consistently underperforming.
If you’re using a shared IP, poor bounce management can even affect others on the same IP, so it’s in everyone’s best interest to keep things clean.
Some ESPs will only provide an overall “Bounce rate” metric on your dashboard or overview campaign reports. To get a deeper level of data (as mentioned above) you may need to look for a more detailed report or create a custom one.
Common causes of high bounce rates
- Old or inactive data: If you’re emailing subscribers who haven’t engaged in years, expect more invalid addresses.
- Purchased or scraped lists: Still happening in 2025 and still a bad idea.
- Poor form validation: No typo protection = more junk data entering your list.
- High send volumes after inactivity: Warming up isn’t just for new IPs. Sudden large sends after a long gap can cause spikes in bounces (and complaints).
How to reduce your bounce rate
- Use double opt-in if you’re seeing a large number of bounces or regularly collecting typo-ridden addresses or spam traps. I’m not a huge fan of it myself, as it slows down the customer journey but in cases where list quality is suffering, it’s a useful short-term fix to regain control.
- Clean your list regularly. Remove unengaged subscribers and anyone who bounces. Tools like NeverBounce etc can check for known invalid and inactive email addresses.
- Monitor new sign-ups and set up alerts if bounce rates spike post-acquisition.
- Validate emails at point of entry (especially for competitions or gated content). Tools like NeverBounce, KickBox and BriteVerify can embed on your website to do this for you.
- Warm up slowly if reactivating a dormant list. Start with small sends to your most engaged dormant customers, then gradually include those with lower engagement.
- Use smart segmentation that relies on engagement data. Define your brand’s thresholds for inactivity (e.g. lack of email engagement like opens or clicks) and lapsing (e.g. time since last purchase) in a way that aligns with your purchase cycle. Once a customer hits those thresholds, stop emailing them.
- Monitor bounce rate over time for your BAU campaigns and automations. The biggest issue I see is when teams aren’t tracking this regularly. Aim to review bounce performance on a continuous basis – I recommend at least month over month (MoM) as a baseline.
Pro tip 💡: Inbox providers like Gmail and Apple now regularly purge inactive addresses. As a rule of thumb, if someone hasn’t engaged in over 12 months, it’s best to stop emailing them or risk unnecessary bounces.
Final thought
Your bounce rate isn’t the most glamorous stat. But it’s one of the quietest warning signs your email program can give you.
Stay on top of it, and you’ll protect your deliverability, improve performance, and avoid bigger headaches down the line.
If you’re not currently tracking your bounce rates or need help figuring out what’s causing the spike, I offer audits that dig into deliverability, data quality and acquisition flows. Drop me a message if you’d like to chat.