Communication with client before submitting proposal

[bernard_1]

How can I contact a client urgently for a question before submitting a proposal. Example:
Reverse engineer an algorithm from clean dataset

"we have a dataset with 2 variables and one constant and need to reverse engineer an algorithm to predict the constant"

This is actually not possible to do unless the algorithm is the constant itself (trivial). So either this is a mistake in the formulation of the problem statement, or the project is inappropriate.

[iamchunchunchun]

You can spend 2 connects and ask the questions in the proposal.

[bernard_1]

Thanks for the idea. But I was asking how I can contact the client before the proposal. Especially in the case where the job is at the edge of being inappropriate. I could equally flag the job as inappropriate with the aim of getting a question answered except it might not work technically. What I am trying to say is that the upwork system is cumbersome. Any auction site will allow questions to be asked that can be seen by all members, and then the client is enncouraged to answer otherwise the client would be seen as unresponsive. I don't want to waste my time with clients engaging in activities that are against my interests.