How to send mail from client's email address?

Question

Email

Good afternoon fellow developers!
I have the honor to ask you a question.
Somehow I couldn’t google it, so I’ll try to describe the essence.
The service has a feature, sending messages through the site to other people.
For now, the solution was to use the reply-to field.
Headers like:
from: <Customer Company name> [email protected]
reply-to: [email protected]
But still, answers sometimes get to us and not to those who need it and have to send them manually.
What are the approaches to solve this problem?
So to say, so that the answers are most likely to get to the mail of customers and not to us the mail of the service.
I will be very grateful for your answers!
Have a nice day everyone!

Answer 1

it all ended in 2001
now everyone is smart and looks at from: reply-to: according to their mood, if antispam is on ML - can reply-to and skip it, filtering by content

Answer 2

Technically, if there is your sender in the SMTP session, and a spoofed + in the body of the letter, you have it configured for your sender domain: spf, dkim, dmarc, arc and a normal reputation of un, then for most senders your letter will reach, possibly spam. There will be a reject only if the domain of the spoofed sender uses dmarc policy reject.
Well, you should understand that over time, with the widespread implementation of dmarc, this will work worse and worse.