diff --git a/protovalidate/internal/extra_func.py b/protovalidate/internal/extra_func.py
index ceeb431f..530bb470 100644
--- a/protovalidate/internal/extra_func.py
+++ b/protovalidate/internal/extra_func.py
@@ -137,7 +137,7 @@ def cel_is_email(string: celtypes.Value) -> celpy.Result:
     if not isinstance(string, celtypes.StringType):
         msg = "invalid argument, expected string"
         raise celpy.CELEvalError(msg)
-    m = _email_regex.match(string) is not None
+    m = _email_regex.fullmatch(string) is not None
     return celtypes.BoolType(m)