validate_email - BigQuery

SELECT `justfunctions.eu.validate_email`("12/[email protected]")
                                            
/*--Output--
0
*/

CREATE OR REPLACE FUNCTION `your_project_id.your_dataset_id.validate_email`(`email` STRING) 
  RETURNS INT AS (CASE
   WHEN NET.REG_DOMAIN(lower(email)) IS NULL THEN 0
   WHEN REGEXP_CONTAINS(lower(email), "^[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*@(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])$") THEN 1
   ELSE 0
END
)
  OPTIONS ( description = '''Validates if an <email> address is properly formatted.''')

SQL User Defined Function (SQL UDF)