> For the complete documentation index, see [llms.txt](https://docs.gmetri.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.gmetri.com/metaverse/publishing/authentication/email-with-otp.md).
# Email with OTP
This allows your viewers to login by entering their email and an OTP. You can also whitelist the domains you want to allow, or directly select most commonly used email domains like gmail.com/outlook.com etc.
To authenticate your deployment with the Email with OTP option, you first need to create a [Viewer Group](/metaverse/sdk/gmetri-sdk-apis/viewer-group.md) (steps below). And then select that viewer group as the access method for the deployment in question.
## Creating a Viewer Group for "Email with OTP"
Creating a Viewer Group for Email with OTP
### Types of Filters
Types for filters for Email with OTP Viewer Group
* Public - allows all emails
* Filter by domain - you can provide a comma separated list of email domains you want to allow (eg: `walmart.com, google.com` )
* Common Email Domains - allows most of the common email domains, while ensuring that disposable email domains aren't allowed.
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