If you are having a deal or an agreement or a negotiation of some kind. Do it via email.
If you had communication offline or via another medium that is not documented, send a mail stating the minutes of the meeting and agreement.
If necessary ask for a confirmation reply.
I used to think this is disrespectful as I most of the time I had communication with the person offline but as humans, we all of us forget.
The email is for your future and the receiver’s future self.
In case, if a person or company or even you yourself deny the deal, you have a written “official” mail which cannot be repudiated.
Most people and companies are normal but some are malevolent. You’ll thank your past self for the email.
If you had offline interation
To not look robotic, mention to the person that you’ll be dropping a mail mentioning discussed points and would require confirmation.
I learned this from my managers and my father.