def test_email_to_mailbox_underscores_retained():
    result = email_to_mailbox_name('*****@*****.**')
    assert result == 'foo_b_exampleorg'
def test_email_to_mailbox_uppercase_lowercased():
    result = email_to_mailbox_name('*****@*****.**')
    assert result == 'foo_exampleorg'
def test_email_to_mailbox_invalid_stripped():
    result = email_to_mailbox_name('*****@*****.**')
    assert result == 'foob_exampleorg'
def test_email_to_mailbox_simple():
    result = email_to_mailbox_name('*****@*****.**')
    assert result == 'foo_exampleorg'
def test_email_to_mailbox_empty_string():
    with pytest.raises(ValueError):
        email_to_mailbox_name('')
def test_email_to_mailbox_all_invalid():
    with pytest.raises(ValueError):
        email_to_mailbox_name('*+@')