from

O PrivacyOptions=authwarnings

to

O PrivacyOptions=noexpn,novrfy,noreceipts,needmailhelo

PrivacyOptions=opt,opt,…

[p] Set the privacy options. ``Privacy'' is really a misnomer; many of
these are just a way of insisting on stricter adherence to the SMTP
protocol. The options can be selected from:

public Allow open access
needmailhelo Insist on HELO or EHLO command before MAIL
needexpnhelo Insist on HELO or EHLO command before EXPN
noexpn Disallow EXPN entirely
needvrfyhelo Insist on HELO or EHLO command before VRFY
novrfy Disallow VRFY entirely
restrictmailq Restrict mailq command
restrictqrun Restrict -q command line flag
noreceipts Don't return success DSNs
goaway Disallow essentially all SMTP status queries
authwarnings Put X-Authentication-Warning: headers in messages

The goaway pseudo-flag sets all flags except restrictmailq and
restrictqrun. If mailq is restricted, only people in the same group as
the queue directory can print the queue. If queue runs are restricted,
only root and the owner of the queue directory can run the
queue. Authentication Warnings add warnings about various conditions
that may indicate attempts to spoof the mail system, such as using an
non-standard queue directory.

PostmasterCopy=postmaster

[P] If set, copies of error messages will be sent to the named
postmaster. Only the header of the failed message is sent. Since most
errors are user problems, this is probably not a good idea on large
sites, and arguably contains all sorts of privacy violations, but it
seems to be popular with certain operating systems vendors. Defaults to
no postmaster copies.