Marketpress is not sending out order confirmation emails.

We have had Marketpress working for us for quite sometime. Everything has been good up until a couple of months ago. When orders were placed on our site Marketpress stopped sending out order confirmation emails. I have throughly checked all email accounts and settings on our end and the email paths and the accounts are working just fine. Test emails from Wordpress are working just fine. Unfortunately, there is no real way to test Marketpress without inputting an order.

I am using WP-Mail-SMTP Version 0.9.5 plugin to reconfigure the wp_mail() function to use SMTP instead of mail(). I am also using Paypal Payments Pro, which is working just fine.

Is there something that I may have overlooked? Can you please give me some guidance as to what may be the issue?