The useful idea
Start with the problem, the affected people and the result you would value.
Describe the situation
Tell us what happens today, who is affected and why the work matters now. One representative example is often more useful than a long requirements document.
Describe a useful result
Explain what should be easier or different when the work is done. Share any known deadline, constraints and budget range. Unknowns can remain unknown at this stage.
Keep the first message simple
Do not send passwords, customer records or confidential system details. We can agree how to handle necessary information after establishing fit.