This is to answer your question.
这是对您所提问题的回答。
This is to answer your question about the long-term lease of our cars.

这是对您有关我们长期租车做出的回答。

Please keep this e-mail for your records.
请妥善保存该邮件，以便您留存记录。
Please keep this e-mail for your records. This e-mail contains an important verification code that you will need if you forget your password.
请妥善保存该邮件，以便您留存记录。如果您忘了密码，该邮件含有您需要的重要的验证码。