This script checks for registered mailers that you have available:

#!/usr/bin/perl

use strict;
use warnings;
use Email::Send;

my $sender = Email::Send->new( { mailer => 'SMTP' } );
$sender->mailer_args( [ Host => 'localhost' ] );

my @available = $sender->all_mailers;

print "@available\n";

[download]

As for the reason why it succeeds with "unknown user", three things come to mind. First, you'll need to open Postfix's main.cf configuration file, for example, /etc/postfix/main.cf. Look for "soft_bounce"---thats where mail that would ordinarily bounce remains queued. Set that to soft_bounce = no. Second, look for "ignore_mx_lookup_error"---that ignores DNS MX lookups that produce no response. Set that to ignore_mx_lookup_error = no. Third, there's another entry that might be there. Look for "smtp_defer_if_no_mx_address_found"---Set that to smtp_defer_if_no_mx_address_found = yes.

In reply to Re^5: Email::Send succeeds with "unknown user" by Khen1950fx
in thread Email::Send succeeds with "unknown user" by Cagao

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