The -bv command-line
switch causes sendmail to verify the list of
recipients. Each recipient in the list of recipients is fully
processed up to the point of delivery without actually being
delivered. If mail can be successfully delivered to a recipient,
sendmail prints a line such as one of the
name ...deliverable: mailer $# value, host $@ value, user $: value
The first form is that of pre-V8 sendmail. The
second form began with V8.1 sendmail.
The name is the original recipient address
after it has undergone aliasing and rule set rewriting. A local
user's name expands to the contents of that
user's .forward file. A mailing
list expands to many names (and produces many lines of output). The
mailer, host, and
user correspond to the triple
returned by rule set 0 (Section 19.5). If no
$@ is returned, the host part
is omitted from this output.
If the recipient cannot be delivered to,
sendmail instead prints the following:
The reason the recipient is undeliverable can be
explained by any of many possible error messages (such as
"No such user") that would prevent
The -bv switch also prevents
sendmail from collecting any mail message from
its standard input unless the -t command-line
switch (-t) is also given.
Beginning with V8.12, the restrictexpand keyword
for the PrivacyOptions option causes
sendmail to drop special privileges when the
-bv switch is specified by a user who is neither
root nor a trusted user. This prevents ordinary
users from reading ~/.forward files, :include:
files, and private aliases (aliases found in
aliases files that are not ordinarily readable).
The restrictexpand keyword also prevents the
-v switch from being used.