## Syntax
```mermaid
%%{init: {
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flowchart LR
Start((START)) --> IS_EMAIL[IS_EMAIL]:::quoted
is_email -->| | IS_EMAIL
IS_EMAIL --> End((END))
```
## Purpose
The `IS_EMAIL` SQL function valuates to boolean true when the value provided is a valid email address according to RFC 822.
Parameters:
- Email: email address.
- Allow plus sign: indicator whether the use of a plus sign ('+') to introduce an alias is allowed (defaults to false).
- Check TLD: indicator whether the TLD of the domain name must be validated against the current list (defaults to true).
Returns: True when the value provided is a valid email address.