Thanks for that Captain Obvious. I wasn't assuming anything

Yes, your program assumes that ->new will succeed, since you wrote it, you assumed that

- I clearly pointed out that the method call is failing, but it's unclear why.

Sure it is, its because ->new failed and $smtp is undef

#!/usr/bin/perl --
use Net::SMTP;
Net::SMTP->new(
) or print "DANG!\n\$! @{[int$!]} $!\n\$^E @{[int$^E]} $^E\n\$@ $@ ";
print "\n", '#' x 10, "\n";
Net::SMTP->new(
    Host    => '127.0.0.1',
    Port    => '6666',
    Timeout => 0.1,
) or print "DANG!\n\$! @{[int$!]} $!\n\$^E @{[int$^E]} $^E\n\$@ $@ ";
print "\n", '#' x 10, "\n";

__END__
DANG!
$! 2 No such file or directory
$^E 10038 An operation was attempted on something that is not a socket
$@  
##########
DANG!
$! 10060 A connection attempt failed because the connected party did n
+ot properly respond after a period of time, or established connection
+ failed because connected host has failed to respond.
$^E 6 The handle is invalid
$@ Net::SMTP: connect: timeout 
##########
[download]

OK, I take that back. Sorry - your reply seemed narky.

Its all good :) all self-evident truths seem snarky when stated -- I should have been more explicit/specific about which call failed

The Basic debugging checklist says 7. Check the return (error) status of your commands , the same goes for methods, including constructors :)

Though in all honesty, I was feeling snarky that day :)