I can't get my head around this. I want to find out if the SMTP server I'm talking to supports the DSN extension (RFC1891). Any help is appreciated, this is what I thought would work: 
use strict;
use Net::SMTP;
my $smtpd = shift @ARGV || 'localhost';

my $smtpc = Net::SMTP->new($smtpd,
    Debug => 1,
);

warn "DSN not supported!" unless $smtpc->supports('DSN');

[download]
The warning is always printed, even if the SMTP server I'm talking to supports the DSN extension. (I've tried this with other SMTP extensions too and the results are the same)

I know I'm doing something wrong here when I call the (undocumented) supports() method in Net::SMTP but I don't know what I'm doing wrong there or what else I could do to achieve what I want.

In reply to Finding supported ESMTP Extensions with Net::SMTP by dub4u

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