Actually, portability was one of my primary concerns in making the case for using the module(s). If you have, for example, a Web server farm, are you going to run a mail daemon on each of those boxes? For security reasons alone, probably not. Sure, you can use mail, but with no mail daemon, it's going to look like you sent the message, but in fact, you just created a file on disk that is never going to be processed.

This is what I use:

my $mailer = Mail::Mailer->new('smtp', Server => $my_local_smtp);

This just opens a connection to the local SMTP server, whatever that is, and drops off the message to be sent. The retrying, error handling, and so forth, they are taken care of by that process, wherever it may be. If it takes a significant amount of time to resolve the DNS for your local mail server, you've got to wonder what the heck is wrong with your ISP. That queueing and retrying is done by the SMTP server, not you. Your script can move on the instant you're finished writing to the socket, and that should't take very long at all.

One of the things you can count on is that there is going to be a suitable SMTP-type service at your provider, if you don't already run one yourself. You can't assume with the same degree of confidence that everyone's going to have a working 'mail' or 'mailx'. Just because it's there doesn't mean it's plugged in.