Notes about confirmation email troubleshooting.
Confirmation emails sent with the local hostname go to spam, and Mail::Sendmail does seem to support SMTP auth very well. I could not get Mail::Sendmail to work with smtp.gmail.com. I also had no luck with Email::Sender::Transport::SMTP which is already a dependency, or Email::Sender::Transport::SMTPS
The best soultion I've found is Email::Send::SMTP::Gmail which works well and has bonus features like support for file attachments. To use it, install it (cpanm Email::Send::SMTP::Gmail) and make sure the gmail account being used for login has the 'allow access for less secure apps' setting turned on.
Here's a test script for proof of concept: