Email could not be sent.  Check your email configuration on the Email/Setup Tab.

Google recently introduced a new email setting that may cause connections to the Gmail SMTP server to fail.  Under My Account > Sign-In & Security > Connected Apps & Sites you will find the new setting called "Allow less secure apps"  

When this setting is turned off, you can't connect to Gmail accounts with much, except Google devices. When set to off, this can prevent connections from PDshop to the Gmail SMTP servers, causing the sending of emails to fail.  In order to send email you will need to make sure this setting is "ON"  

Below are the Gmail settings you will need to use in PDshop's Admin:
SMTP SERVER: smtp.gmail.com
SMTP PORT: 587
Enable Secure Connection: Checked
Google's "Allow less secure apps" setting must be ON.

Is PDshop's email features really Less secure?  
NO! Unfortunately, Google's wording is a bit misleading, it should read "non-Google" devices/apps, rather than less secure. PDshop uses the best encryption available in Microsoft's Asp.Net platform.  So long as you have "Enable Secure Connection" checked, PDshop is connecting using the latest available TLS protocol.  TLS is the current industry standard; it's the same protocol web browsers use for securing web pages when you submit credit card details to a website.