Let me know if you are interested.
如果您感兴趣，请告诉我。
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.

如果您对我们的提议感兴趣，请告诉我。如果您有任何问题，请尽管联系我们。另外，如果您需要更多的信息，请联系杰森.李先生，他会为您提供您所需要的信息。

Thanks you for submitting a proposal to us.
感谢您提交给我们的提案。
We appreciate your interest in submitting a proposal.
感谢您对提交提案感兴趣。
I’d like to thank you for the letter of proposal, which you submitted to us on March 29.
我想感谢您在3月29日向我们提交的提案。