How to disable probing the existence of users on my Postfix?

Question

Email

Some soap validation services - not **format** soaps, **but the soaps themselves** - try to connect to the soap being validated and check if the user exists:
Connected, got to the login, realized that the user exists - it's done, turn off.

localhost postfix/smtpd[28911]: NOQUEUE: reject: RCPT from aabbccdd[11.22.33.44]: 550 5.1.1 <[email protected]_domain.com>: Recipient address rejected: User unknown; from=<[email protected]> to=<[email protected]_domain.com> proto=SMTP helo=<something_bla_bla>
    
    localhost postfix/smtpd[28911]: disconnect from aabbccdd[11.22.33.44] helo=1 mail=1 rcpt=0/1 quit=1 commands=3/4

How can this be controlled on my postfix server?
That is, how
to a) prohibit such probing altogether?
b) how to make it always return "yes, the user exists"? to confuse probingers
. And normal password authentication and email sending should continue to work as usual.

Answer 1

Set up fail2ban

Answer 2

Some mail servers may check the sender's address this way.

Answer 3

Score.
At one time, I had it set up so that mail for non-existent users fell to the "user" spamtrap, whose mailbox was periodically cleared. But such a feint with the ears can do more harm than good when it turns out that the partners sent an important document to the address of the manager who quit yesterday and did not receive a thrashing, they began to wait for an answer - but there was nothing from our side, because the letter "accepted" spamtrap...
In addition, counter-checking the validity of soap is a trick of some anti-spam programs, for example, rambler.ru

Answer 4

Such probing cannot be prohibited.
And if the honest sender made a mistake in the address of the recipient?
There is also a sender check with a callback (10% of spam is eliminated on it).