如果你愿意，你能告诉我你的邮箱地址吗？用英文怎么说？

If you want,could you tell me your e-mail address?

Can you tell me your E-mail address,I mean if you'd like to?

If you will, could you tell me your email address?

If possible, would you tell me your e-mail.如果可以的话,你能告诉我你的邮箱吗? 个人感觉更地道些.

could you tell me your e-mail if you are willing

Could you tell me your e-mail address? <如果你愿意就已经包含在could里面了>