v0.4.0: support test accounts (#7)
`export EMAIL_TEST_ACCOUNT_a_at_test_com=123456` then (pretend) send email to `[email protected]`, verify token using the preset value `123456`.
`export EMAIL_TEST_ACCOUNT_a_at_test_com=123456` then (pretend) send email to `[email protected]`, verify token using the preset value `123456`.