High Hard Bounce rate

Marketing & Content Hub Email Deliverability
1

Hi Community,

I recently ran few email campaigns and noticed a high hard bounce rate. Out of 5635 of recipients, a significant portion resulted in hard bounces (80).

I’m looking to understand:
What best practices should I follow to reduce hard bounces in future campaigns?
I am also running the lists thru NeverBounce to improve deliveribility.

Any insights, troubleshooting tips, or workflows that have worked for you would be greatly appreciated.

Thanks in advance!

2

Hi @Deep_Kwatra,

If you’re running your list through an email validation tool, then you’re already following a major best practice. This will help reduce your hard bounce rate a log.

Also keep in mind that HubSpot will automatically exclude hard bounced contacts from future email sends. The same contacts will not bounce twice, unless you remove their hard bounce in between.

As overall best practices, here’s what I’d recommend:

  • Make sure your email sending domain is fully authenticated to avoid policy bounces: Manage your email authentication
  • Do not send marketing emails to purchased lists or contacts that do not expect to hear from you
  • Validate lists again that were last sent emails a long time ago ( = revalidate lists on a regular basis)

Best regards!

3

Hi @Deep_Kwatra,
Start with dynamic lists that segment contacts by how recently they’ve engaged for example, last activity within 30, 60, or 90 days.

It’s also worth regularly removing contacts who have previously hard bounced, unsubscribed, reported spam, or haven’t shown any activity for a long time. Look at engagement rates like open and click rates, and filter out the consistently unengaged before sending.

For new imports, always validate before adding them into HubSpot (as you are using neverbounce), and avoid lists from unknown or purchased sources.
You can setup an workflow in HubSpot to automatically unenroll bounces, flag repeated soft bounces, and funnel inactive contacts into re-engagement campaigns can go a long way in keeping your database healthy and deliverability strong.

4

I agree with both answers given. Another safeguard would be to do a double opt-in. This would have the user confirm via email that they do want to receive emails from your team. This may lower opt-in rates significantly, but you have a much cleaner list.

5

Hi,

A hard bounce rate like this usually points to list quality issues, so the main improvement comes from tightening how contacts are collected and uploaded.

Here are practical steps you can take:

Verify emails at the point of capture
You can add real-time email validation on signup forms so invalid emails never enter your system in the first place.

Clean old and imported lists properly
Run all historical or imported contacts through NeverBounce (which you’re already doing) and remove anything invalid or risky, not just unknown.

Avoid using outdated or third-party lists
These are the most common source of hard bounces, even if they look large or active.

Segment and monitor new sources separately
Keep new leads from ads, forms, and imports in separate lists so you can quickly identify if one source is causing higher bounce rates.

Set up regular list hygiene
Don’t treat it as a one-time cleanup - schedule periodic validation and removal of inactive or invalid emails.

In most cases, fixing the source of the data makes a bigger difference than anything else.