Port 587 requires authentication. Did you give a username and password under %opts? The example from Net::SMTP::TLS: 
#!/usr/bin/perl

use strict;
use warnings;
use Net::SMTP::TLS; 

my $mailer = new Net::SMTP::TLS( 
        'your.mail.host', 
        Hello => 'some.host.name', 
        Port => 587,
        User => 'emailuser', 
        Password=> 'password'); 

$mailer->mail('emailuser@your.mail.host'); 
$mailer->to('someonecool@somewhere.else'); 
$mailer->data; $mailer->datasend("Sent thru TLS!"); 
$mailer->dataend; $mailer->quit;

[download]
First, note the use of Hello. It's the hostname used in the EHLO command.

Second, if you are using Postfix, then you'll need to check the config. You might need to specify port 587. For example, find your config and list your transport something like: 

transport=Net::SMTP::TLS user@exmple.com Password 12345 Port 587

[download]
Check the documentation of Postfix for more info.

In reply to Re^3: add to MIME::Lite support for smtp tls on port 587 by Khen1950fx
in thread add to MIME::Lite support for smtp tls on port 587 by swilting

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