Using with zod. How to ignore empty field when "onBlur"?

[Toshinaki]

I have a signin form, with email & password fields, and the email field is auto-focused.
There's also a "forgot password" link the redirect user to another form.

I'm using zod and onBlur to check if the inputs are ok:

const signinSchema = z.object({
  email: z.string().email(),
  password: zStringRequired(),
});

Since the mode is onBlur and the email field is auto-focused,
if I click away and leave the email empty, the check was triggered, and says invalid email.

How to skip check on this not dirty (or not touched? I'm not sure) and empty email field?