Specific email address field in form shows 'Please enter a valid email address.'

Marketing & Content Hub Email Deliverability
1

A specific email address field in the form is displaying the message “Please enter a valid email address.” What steps can I take to resolve this issue?

I am using an email address with a custom domain.

Chat support directed me here, stating that this is a “technical issue.”

Thank you in advance.

3

Hi @taneCREATIVE and welcome, it’s a pleasure to have you on the HubSpot Community! :confetti_ball:

Thanks for reaching out!

In forms, the email field has validation on more than just the format of the address. It also checks whether the domain’s top-level domain is recognized, whether the domain has valid DNS records like MX or A records, whether the domain is blocked, and whether the address has deliverability-related issues.

To troubleshoot, I’d recommend testing another email address on the same domain, checking that the domain has valid DNS records, and trying the form in an incognito window to rule out browser-related interference.

I’d love to put you in touch with our Top Experts: Hi @danmoyle, @EugeneAtKiwi and @CarolinaDeMares do you have suggestions to help @taneCREATIVE, please?

Thanks so much and have a wonderful day!
Bérangère

4

Welcome to the Community @taneCREATIVE! HubSpot’s email field in their forms is doing more than checking for the @ sign, so a custom-domain address can still be rejected if it fails formatting, domain, DNS, or deliverability checks. HubSpot says the message appears when the email does not pass immediate validation, including public-suffix formatting, its automatic domain blocklist, DNS/MX or A-record lookup, or a global blocklist.

  • Here’s what I’d do to troubleshoot:
    Confirm there are no extra spaces, typos, or unusual characters in the address, and that the top-level domain is a valid public suffix.
  • Test the same form with a different address from a known-good domain to see whether the issue is specific to that one email or the form itself.
  • Make sure your custom domain has working DNS records, especially an MX record or at least an A record, because HubSpot checks for those before allowing submission.
  • Check whether the domain or address is on any blocklist, including HubSpot’s automatic blocked domains or a global block for deliverability reasons.

And from what I found in the HubSpot Knowledge Base, here’s what else I’d check in HubSpot settings. Look in the form’s email field settings for any blocked-domain rules, including “Email domains to block” or “Block free email providers.” HubSpot lets you block specific domains or its default list of free providers. If the form was customized, ask your developer whether any custom JavaScript, regex validation, or an external verification service is rejecting the address before submission. HubSpot supports custom validation only through a custom build or the Forms API.

It sounds like it’s one specific email address. If that’s the case and others on the same domain work, the address itself may be caught by a suppression or reputation rule rather than a general domain problem. In that case, try the address on a different HubSpot-powered form or test with another mailbox on the same domain to isolate whether the rejection is address-specific.

A practical workaround I found suggested from my AI research is to “collect the email in a plain text field temporarily, then move it into the Email property after validation, but that is only advisable if your workflow can safely handle the extra manual step.”

I hope that helps!

5

Hey @taneCREATIVE ,

Besides what others have already suggested in this thread, I’d also recommend checking if you have any custom validation rules enabled. Go to Settings → Properties → find your email property and click on it → go to Rules on the left menu. See which options are toggled and if any of them might be causing that specific email to fail validation.