HubSpot email validation, via API
You can validate emails for HubSpot by calling Trueguard's email validation API from your HubSpot form workflow or backend before a contact is created. It checks format, MX records, SMTP deliverability, disposable domains, catch-all, role-based, and free-mail in one call, so fake and undeliverable addresses never enter your HubSpot contacts. There is no native app required.
The problem
The cost of junk contacts in HubSpot
A junk contact does not announce itself when it syncs. The damage shows up later, in bounce reports, sender reputation drops, and wasted contact quota.
Sender reputation damage from dead contacts
Every bounce on a HubSpot marketing send lowers your sender score. Enough bounces and subsequent sends land in spam, including the mail to contacts who are genuinely engaged.
Wasted contact quota on junk records
HubSpot tiers are priced on marketing contacts. Fake, disposable, and undeliverable addresses count against that limit whether you ever send to them or not.
Skewed segmentation and workflow data
Junk contacts pollute your lists, throw off segment sizes, and cause automation workflows to fire on records that will never convert. Reports drift from what is actually real.
Catch-all contacts cleared as deliverable
HubSpot's native check does not detect catch-all domains. Addresses on catch-all domains accept every mailbox, so a junk address passes the form check and enters your contact list as apparently valid.
*Impact examples are illustrative. Actual results depend on your HubSpot tier and list mix.
How it works
How do you validate emails for HubSpot?
You validate emails for HubSpot by calling Trueguard's API at the point where a contact is about to be created or synced. There is no marketplace app to install. This is an API call you wire into your own flow, and that is the honest shape of it.
There are two common places to put the call. The first is your form handler. If your HubSpot form posts to your own backend before it creates the contact, you call the email verification API there, read the verdict, and only create the HubSpot contact for the addresses you accept. The second is a custom-coded action inside a HubSpot workflow. If the contact is already in HubSpot, a workflow can pass the email to your endpoint, which calls Trueguard, and write the result back onto the contact as a property you can branch on.
Either way, the pattern is the same: the address goes to Trueguard, Trueguard returns format, MX, SMTP deliverability, disposable, catch-all, role-based, and free-mail in one response, and your flow decides what HubSpot does with the contact. You own where the call sits. Trueguard owns the verdict.
No native HubSpot marketplace app required. No connector to install.
The signals
What does Trueguard check before an email enters HubSpot?
One call returns seven signals per address, each a contact-quality flag you can act on before the record lands in HubSpot. Catch-all is returned as risky, not unknown, because the server confirms the domain but not the specific mailbox.
Format and MX records
Format checks the address against RFC 5322. MX confirms the domain actually publishes mail servers. A domain with no MX cannot receive mail, so the address is invalid no matter how it is typed. These catch the obviously broken contacts before they sync.
SMTP deliverability
A live handshake to the destination server that stops before any message is sent. It reads whether the mailbox would accept mail. This is the signal HubSpot's own form check does not have, and it is what separates a deliverable contact from one that will bounce on your first marketing send.
Disposable and catch-all
Disposable detection flags throwaway domains against a continuously updated registry. Catch-all detection flags domains that accept every address and returns them as risky. Both keep low-value addresses from quietly filling your contact list and burning marketing-email quota.
Role-based and free-mail
Role-based (info@, sales@) and free-mail (Gmail, Outlook, Yahoo) are context flags, not rejections. They tell you whether a contact is a named person at a company or a shared inbox, which is useful for segmentation and lead routing inside HubSpot.
Why does HubSpot say "email validation failed"?
Debugger answer
If HubSpot says "email validation failed," that message is from HubSpot's own built-in form check, not from Trueguard.
HubSpot validates form emails at the format and domain level. It blocks addresses that are not shaped like a valid email, and it can block submissions from free or personal email domains when a form is set to require a business email. So a "validation failed" message usually means one of three things: the address has a syntax error, the domain does not resolve as a real mail domain, or your form is configured to reject free providers like Gmail and the submitter used one.
That native check is shallow on purpose. It confirms the address looks right and the domain exists. It does not open an SMTP handshake, so it cannot tell you whether the mailbox actually accepts mail. It does not check a disposable registry, so a throwaway address on a real-looking domain passes. It does not detect catch-all behavior. A contact can clear HubSpot's validation and still be undeliverable, disposable, or a catch-all that will never confirm.
That is the gap a dedicated API fills. Trueguard runs the deeper layer HubSpot's form check skips: SMTP deliverability, disposable detection, and catch-all detection on top of format and MX. You keep HubSpot's native check for the obvious cases and call Trueguard before the contact is created to catch the addresses that pass HubSpot but still should not enter your list. The two are not in conflict. HubSpot rejects the malformed; Trueguard catches the deliverable-looking but undeliverable.
The decision
Which contacts should enter HubSpot and which should not?
Each status maps to a contact-management decision before the record enters HubSpot.
| Result | What it means | HubSpot action |
|---|---|---|
| safe | Format, MX, and SMTP confirm a real, deliverable mailbox. | Create the HubSpot contact and proceed with normal nurture. |
| risky | Deliverable at the server but unconfirmed at the mailbox. Catch-all, role-based, or free-mail flagged here. | Create the contact with a flag property. Route to a review list or lower-priority workflow before outreach. |
| invalid | Bad format, no MX, or the server rejected the address. Undeliverable. | Do not create the contact. Reject at the form or skip the sync. This address will bounce. |
| unknown | The server blocked the probe or gave no clear answer. | Create the contact with a flag. Monitor for engagement before investing in heavy outreach. Re-check if needed. |
What it means
Format, MX, and SMTP confirm a real, deliverable mailbox.
HubSpot action
Create the HubSpot contact and proceed with normal nurture.
What it means
Deliverable at the server but unconfirmed at the mailbox. Catch-all, role-based, or free-mail flagged here.
HubSpot action
Create the contact with a flag property. Route to a review list or lower-priority workflow before outreach.
What it means
Bad format, no MX, or the server rejected the address. Undeliverable.
HubSpot action
Do not create the contact. Reject at the form or skip the sync. This address will bounce.
What it means
The server blocked the probe or gave no clear answer.
HubSpot action
Create the contact with a flag. Monitor for engagement before investing in heavy outreach. Re-check if needed.
Try one address
The same check your HubSpot workflow would call. Paste any address and see the verdict.
Paste an address above. Or try one of the examples below.
Pricing
Start free. The first 100 validations a month are free with no card, enough to wire the call into one HubSpot form workflow and watch the contacts land clean. The same check ships in the email verification API at $49.99 a month for 50,000 validations, then $0.001 per validation beyond that. To check one address by hand before you build anything, run it through the free email verifier.
Pay for what you check. Cancel anytime. Overage is billed through Stripe at $0.001 per validation regardless of volume.
What counts as a validation? One request to the validation endpoint is one validation. Failed calls (4xx from your side) do not count.
Contact quality
How does this keep your HubSpot contact list clean?
Every junk address that becomes a contact costs you something: a bounce, a slice of your marketing-email reputation, and a contact slot against your tier. Validating before the contact is created keeps all three out of HubSpot.
Fewer bounces on your sends
Addresses confirmed deliverable before they become contacts do not bounce when HubSpot emails them later. You remove the addresses that were guaranteed to fail before they ever enter a send, instead of cleaning them up after the bounce report.
Better marketing-email deliverability
A run of bounced sends lowers your sender reputation, which pushes more of your mail to spam, including the mail to contacts who are real. Keeping invalid addresses out of HubSpot protects the deliverability of every legitimate contact behind them. We do not publish a deliverability figure for your account, because that depends on your list and your sending. We remove the part you control at capture.
No wasted contact quota
HubSpot tiers are priced on marketing contacts. Fake, disposable, and undeliverable addresses still count against that limit if they sync. Validating before creation means you are not paying to store contacts that can never be reached.
Cleaner segmentation
Role-based and free-mail flags written onto the contact let you segment and route inside HubSpot. A sales@ shared inbox and a named buyer get treated differently, so your workflows and assignment rules act on accurate data.
No app needed
Do I need a HubSpot app or marketplace integration?
No. There is no Trueguard app in the HubSpot marketplace, and you do not need one. Email validation for HubSpot is an API call you make from your own form handler or from a custom-coded action inside a HubSpot workflow. That is the whole integration.
We are direct about this because it changes how you wire it. You are not installing a connector and clicking through a setup screen. You are adding one HTTP call to a place you control: the backend that processes your form, or a workflow action that has code. The upside of doing it yourself is that you decide exactly when the check runs and what HubSpot does with each result, instead of inheriting a connector's fixed behavior.
If you want code to start from, the email verification API page has working request samples, and the JavaScript email validation and Python email validation guides cover the form-handler and workflow-action cases. The call is the same one used everywhere else; only the place you put it changes.
Related use cases
Signup Form Email Validation
Validate email addresses in real time at registration, before you create the account.
Learn moreLead Form Email Verification
Verify email on lead capture forms before junk addresses sync to your CRM.
Learn moreEmail Validation for Fraud Teams
Use email validation as a standalone fraud signal to catch disposable and fake addresses.
Learn moreFrequently asked questions.
About HubSpot email validation.
How do I validate emails for HubSpot?
You call Trueguard's email validation API from your HubSpot form workflow or your backend. If your form posts to your own server first, validate there and only create the HubSpot contact for accepted addresses. If the contact is already in HubSpot, a custom-coded workflow action can pass the email to your endpoint and write the result back as a contact property. Either way, it is one API call you place in a flow you control.
Is there a native Trueguard HubSpot app or marketplace integration?
No. There is no Trueguard app in the HubSpot marketplace. You validate emails by calling the API yourself, from your form handler or a custom-coded HubSpot workflow action. That is deliberate: doing it as a direct API call lets you control exactly when the check runs and what HubSpot does with each result, rather than inheriting a connector's fixed behavior.
Why does HubSpot say email validation failed?
That message is HubSpot's own built-in form check, not a Trueguard result. HubSpot validates at the format and domain level: it rejects malformed addresses and can block free or personal domains when a form requires a business email. It does not run an SMTP check, a disposable check, or catch-all detection. So an address can pass HubSpot and still be undeliverable. Trueguard adds that deeper layer on top of HubSpot's native check.
Does this stop disposable and fake emails from becoming HubSpot contacts?
Yes. Disposable detection checks each address against a continuously updated registry of throwaway providers, and the deliverability check catches addresses that look real but reject mail. Catch-all domains are flagged risky so you can handle them with care. When you call the API before creating the contact, those addresses are flagged or rejected before they ever enter your HubSpot list.
Will it improve my HubSpot marketing email deliverability?
It removes the addresses that were guaranteed to bounce, which protects the sender reputation that gets your real mail delivered. We do not promise a specific deliverability number, because your actual results depend on your list, your content, and your sending practices. What validation does is keep invalid and undeliverable addresses out of HubSpot, so your marketing sends are not dragging dead contacts that pull your reputation down.
Can I validate existing HubSpot contacts, not just new form fills?
Yes, by calling the API against those contacts yourself. Export or list the addresses, run them through the validation endpoint in a batch from your own script or a workflow action, and write the results back onto the contacts. Be clear that this is your own batch call, not a native sync. There is no automatic background process; you decide when to run it and what to do with the verdicts.
Is there a free tier to test with HubSpot?
Yes. The first 100 validations a month are free with no card, which is enough to wire the call into one HubSpot form workflow and confirm contacts land clean before you scale. For a quick single-address check outside HubSpot, the free email verifier at https://trueguard.io/email-verifier runs the same validation in the browser. When you need more volume, the paid plan is $49.99 a month for 50,000 validations.
