Keep a clear record of supplier questions and answers
A four-column sheet that stops confirmed facts from getting lost in an email thread - and shows at a glance what is still open.
A valve enquiry generates a dozen small facts across several emails: a pressure confirmed, an orientation still open, a material answered for one model but not another. By the time you order, half of them live only in someone's inbox.
Four columns fix it. Keep the sheet next to the enquiry, not inside the email thread.
The four columns
Question - One fact per row, written as a question. "Which connection is the cylinder side on XF-35H?" not "connections".
Status - Open, answered, or superseded. Three values, nothing else.
Answer and who gave it - The answer as given, plus the person and the date. Not your summary of it.
Where it came from - The email, the page, the drawing revision. A fact without a source cannot be re-checked when something changes.
Two habits
Two habits make it worth keeping. First, a question does not get marked answered until the answer names the exact model - an answer about a family is not an answer about a model. Second, when something changes, the old row is marked superseded rather than overwritten, so you can see what changed and when.
Two questions
Is this not what the quotation is for? A quotation carries the commercial terms and the final selection. It does not usually carry the reasoning, and it never carries the questions that are still open at the moment it is issued.
What if the supplier answers "to be confirmed"? That is an answer. Record it as open with the date, so it is visible rather than forgotten.