perl error- Can't call method "domain" on an undefined value - perl

Question

#!/usr/bin/perl -w
use Net::SMTP;
$smtp = Net::SMTP->new('mailhost');
print $smtp->domain,"\n";
$smtp->quit;
I run this pl file and get error "Can't call method "domain" on an undefined value"
and in this pl file:
#!/usr/bin/perl -w
use Net::SMTP;
$smtp = Net::SMTP->new('mailhost');
$smtp->mail($ENV{USER});
$smtp->to('postmaster');
$smtp->data();
$smtp->datasend("To: postmaster\n");
$smtp->datasend("\n");
$smtp->datasend("A simple test message\n");
$smtp->dataend();
$smtp->quit;
I get error Can't call method "mail" on an undefined value
What I need todo ?

Answer 1

Has it occured to you that Net::SMTP may have had problems finding your mailhost, and establishing an SMTP connection? I see that you took your scripts directly from the documentation – you do have to supply an actual value for mailhost.
If you had read the documentation a bit further, especially to the documentation for the new method, you'd have found this interesting snippet:
new ( [ HOST ] [, OPTIONS ] )
This is the constructor for a new Net::SMTP object. HOST is the name of the remote host to which an SMTP connection is required.
On failure undef will be returned and $# will contain the reason for the failure.
So let's print out that reson for failure:
my $mailhost = "your mailhost";
my $smpt = Net::SMTP->new($mailhost) or die "Can't connect to $mailhost: $#";
die aborts your program with an error message. This message should tell you more about the actual error.
Do note that the example code in the documentation is not neccessarily meant to be used for real projects – it is just there to showcase the capabilities of the module. For real code, always use strict; use warnings at the top of your code, and declare all your variables with my. This helps finding more errors.