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How to Validate External Email Addresses in Microsoft Forms

Maira Mehtab Oct 15, 2026 870 views

Question details

The user needs to validate external email addresses submitted by respondents to ensure accurate data entry.

How to Validate External Email Addresses in Microsoft Forms

Product: Microsoft Forms
Device & OS: not provided
Scenario: Collecting contact information from external respondents who are not part of the organization's Microsoft Entra ID directory.
Observed behavior: Standard Microsoft Forms lacks native email validation rules and does not support custom regular expressions (regex), making it difficult to automatically restrict invalid email formats.

Before you start

Verify whether you are using the standard version of Microsoft Forms or an advanced licensed version (such as Dynamics 365 Customer Voice), as custom validation features vary by tier.

Solution 1Recommended

Use Regex Validation in Advanced Forms Products

Use regular expressions to strictly enforce proper email formatting if you have access to an advanced Microsoft Forms license.

If you are using an upgraded Microsoft Forms environment (like Forms Pro / Dynamics 365 Customer Voice), you can utilize custom regular expression (regex) validation to ensure respondents enter a valid email format.

Select the question

Open your form and select the text question intended for collecting the email address.

Access restrictions

Click the three dots (More settings) in the bottom right corner of the question block and choose 'Restrictions' or 'Custom validation'.

Apply regex pattern

Choose the 'Regular Expression' option and enter a standard email validation pattern, such as: ^[\w-]+(\.[\w-]+)*@([\w-]+\.)+[a-zA-Z]{2,7}$

Set error message

Provide a custom error message like 'Please enter a valid email address' that will display if the input does not match the regex pattern.

Use Regex Validation in Advanced Forms Products

Solution 2

Mitigate Validation Limits in Standard Microsoft Forms

Since standard Microsoft Forms cannot validate emails natively, use clear instructions and alternative feedback channels to improve data accuracy.

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Frequently Asked Questions

Can I automatically email respondents if they enter an invalid email address?

No. Sending an automated notification to a respondent regarding an invalid email address is structurally impractical, as the email will simply fail to deliver to the poorly formatted or non-existent address.

Why doesn't my Microsoft Form have a Regular Expression option?

The standard version of Microsoft Forms included with most basic Microsoft 365 plans does not support custom regular expression (regex) validation. This feature is typically reserved for advanced or premium licenses like Dynamics 365 Customer Voice (formerly Forms Pro).

What is the best regex pattern for validating an email address?

A widely accepted and effective regular expression for standard email validation is ^[\w-]+(\.[\w-]+)*@([\w-]+\.)+[a-zA-Z]{2,7}$. This pattern ensures the string contains appropriate alphanumeric characters, an '@' symbol, and a valid domain suffix.

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