I use Kickbox to clean the email list for StoryFolder, a video-storyboarding app I run as the founder. We had an older list of newsletter subscribers that hadn't been cleaned in years, and I wanted to check it before sending to it again. I ran an open-source SMTP checker first, then uploaded the addresses it couldn't get a verdict on to Kickbox as one CSV.

What I like best:

- Upload is drag-and-drop with a CSV, and the file processed quickly.

- Pricing is clear. I bought a 1,000-credit pack for $10 and each address used one credit, so I knew the cost before I started.

- The results file adds columns for result, reason, accept_all, disposable and role, so it was easy to join back to my own list.

- It gave verdicts where my local checker couldn't. Most of the addresses I uploaded came back deliverable, including Yahoo/AOL-family addresses that are hard to check any other way. A small number came back undeliverable, and I suppressed those before sending. Review collected by and hosted on G2.com.

Two things. First, my first checkout was flagged for a manual transaction review, which held up my credits. It was probably a mismatch between my business name and payment details. Kickbox support asked a few short questions and approved it quickly, but I couldn't use the service until they did, so it cost me roughly a day. A clearer notice up front about why a payment gets flagged would help.

Second, "risky" and "unknown" verdicts need judgment. Those two buckets were a small share of my batch, and the results give you the reason but not a recommendation, so you have to decide yourself whether to send to them. I chose to send to them, based on my own engagement history. A short guide to which reasons are safe to send to would make that easier. Review collected by and hosted on G2.com.

The simple UI and pricing were both attractive, and getting a few free trial credits was nice - though we never used them. The price was low enough for our needs I just purchased 2000 credits. Review collected by and hosted on G2.com.

nothing in particular, but we've only tried it on one list so far Review collected by and hosted on G2.com.

What I like best about Kickbox is its accuracy and ease of use. It quickly verifies email addresses, helps reduce bounce rates, and improves overall email deliverability. The interface is clean and intuitive, the API is easy to integrate into our workflows, and the bulk verification feature saves a significant amount of time. It's become an important part of maintaining high-quality contact lists and protecting our sender reputation for outbound B2B sales campaigns. Review collected by and hosted on G2.com.

The main downside is that pricing can become expensive when verifying very large email lists. Occasionally, some addresses are classified as "Risky" or "Unknown," which can make it difficult to decide whether to include them in a campaign. It would also be helpful to have more detailed explanations for verification results and additional reporting features for large-scale list management. Review collected by and hosted on G2.com.

What I like best about Kickbox is how quickly it gives us confidence in our email data. We were able to validate over 500,000 legacy email records, reduce bounce rates to under 0.5% in new market campaigns, and protect our domain reputation while expanding into new markets. It's fast, reliable, and removes the guesswork before we hit send. Review collected by and hosted on G2.com.

The only thing I'd like to see is even more insight into why certain addresses are flagged as risky. The current results are very useful, but having a little more context would make it even easier to decide how to handle borderline cases. Review collected by and hosted on G2.com.

Registration was straightforward, and the UI was simple to navigate. The standout feature for me is the email validation tool itself. After I ran my list through it, my bounce rate stayed within HubSpot’s admissible limits. I also appreciate the credit-based pricing structure, it’s easy to understand, easy to track, and exactly what we needed for cleaning up our list. Only integrated with HubSpot to clean a list and re-upload it to HubSpot to launch an email campaign. The integration with HubSpot was straightforward. Review collected by and hosted on G2.com.

Nothing comes to mind. I had a very specific, time-sensitive need for a tool to clean a list for a client campaign that was about to go out, and the Kickbox setup and validation process was easy peasy. I also understood going in that some of the emails the tool flagged as OK could still bounce. If someone is looking for a 100% validation rate for their emails, I don’t think there’s any tool that can truly guarantee that. Review collected by and hosted on G2.com.

Kickbox is fast and easy to use. It provides you with a detailed report for each contact, with if they're deliverable etc, but also the reason why they may be undeliverable or risky, e.g invalid domain etc. We are based in the uk and the price is very good, they have strict rules which apply to UK regulations on GDPR etc. Review collected by and hosted on G2.com.

Sometimes it can say someone is risky or undeliverable and i can then run them through an alternative platform and it be deliverable, so it leaves me wondering which is correct. However the support your can get is good from kickbox. Review collected by and hosted on G2.com.

I like how easy it is to click a button and rerun unknowns through the system, which makes continuing to clean my data simple. I also enjoy the explanation provided for risky or undeliverable data, as this helps me understand whether an error might be a simple misspelling that can be corrected through the best match feature. This feature saves me time and helps maintain data quality by preventing the loss of potentially valuable contacts. The initial setup was very easy and quick, which I appreciate. Review collected by and hosted on G2.com.

The dashboard is a little bit hard to navigate. I've had a hard time finding where my lists live to download them again. That's the main thing—it could improve the interface. Review collected by and hosted on G2.com.

I loved how easy it was to upload and clean my lists. The entire experience was seamless and effortless. The results were nothing short of exemplary. The price of the product is very reasonable, and when I got stuck, getting additional support was integrated into the dashboard. For those who want deep integrations, that option exists as well. Review collected by and hosted on G2.com.

The free version to test out the product did not allow for enough data to be uploaded. Whilst the pricing was reasonable, I felt it could have offered multiple performance outputs. Review collected by and hosted on G2.com.

What I like best about Kickbox is the Sendex score. Instead of giving me only a yes, no, or risky result, it provides a score that helps me judge the quality of each email address and make better decisions about which contacts to keep or remove. Review collected by and hosted on G2.com.

I wish there were an option to paste in a list of email addresses for verification. Right now, the choices are checking them one at a time or uploading a CSV, which adds an extra step for smaller lists. Review collected by and hosted on G2.com.

We work with a high volume of brand partnerships, newsletters, and outreach campaigns, so email deliverability and list quality are incredibly important to us. Kickbox helps us confidently verify email addresses before campaigns go out, which improves our sender reputation, reduces bounce rates, and saves our team a lot of time.

We appreciate how straightforward the platform is — it integrates smoothly into our workflow and gives us peace of mind knowing we’re reaching real, active contacts. For a content and marketing team like ours, that efficiency makes a big difference. Review collected by and hosted on G2.com.

We’d love to see more seamless integrations and automation features to reduce manual steps in our workflow. While the platform is very reliable overall, a few extra customization and collaboration features would make it even stronger for teams handling high-volume campaigns like ours. Review collected by and hosted on G2.com.