Let me know if you are interested.
如果您感興趣，請告訴我。
Let me know if you’re interested in our proposal. Feel free to contact us should you have any questions. Also, if you need more information, please contact Mr. Jason Lee and he will provide you with what you need.

如果您對我們的提議感興趣，請告訴我。如果您有任何問題，請盡管聯(lián)系我們。另外，如果您需要更多的信息，請聯(lián)系杰森.李先生，他會為您提供您所需要的信息。

Thanks you for submitting a proposal to us.
感謝您提交給我們的提案。
We appreciate your interest in submitting a proposal.
感謝您對提交提案感興趣。
I’d like to thank you for the letter of proposal, which you submitted to us on March 29.
我想感謝您在3月29日向我們提交的提案。