No email receipt to customer

-- url of the page with the problem -- : cmdnet.org//cmd-store
-- HikaShop version -- : 2.3.2 business
-- Joomla version -- : 3.3.1
-- PHP version -- : 5.4.30
-- Browser(s) name and version -- : Chrome (latest)

Running this site with the latest HS version (upgraded from 2.3.1 - originally 2.2)

The customers are no longer receiving an email receipt for their purchase.

The only thing that has changed is updating PHP version.

There was custom modifications of Order Notification email, but I've removed that.

Admin notices of orders ARE being delivered just fine.

Is there a list of places to check that might be causing problems with this particular email being sent?

Are the orders confirmed ?

If not, then you should check here:
www.hikashop.com/support/documentation/i...or.html#notification
If yes, then it's a problem with the emails. You should check the Emails settings of the HikaShop configuration and the emails themselves via the menu System>Emails.