Opencart does not send specific emails

I have installed Opencart 2.0.3.1 in a client's server along with a template. It does not send any mail notification to either the buyer or the admin about an order. I've quadruple checked all the settings, including those for php mail() function. The strange part is that, if I change the status of an order and choose to notify the customer, it works just fine and sends the proper email.

Any ideas of what is wrong?

No answers but questions:

What do you have configured for your mail settings?
Do you use a built in 'domain' email address like order@yourdomain.com or do you use some external like yourdomain@gmail.com?

I also have ran into this issue where the order email isn't received but all the rest are. It is not 100% solved but much improved by removing ALL settings under "SMTP ...." when using "mail".

Mike

I have configured my mail settings for mail(), without any other SMTP settings (they are empty already). I'm using an external email address @hotmail.com.

UPDATE: I've managed to make a small progress with tha issue my disabling the html variable. Specifically:

In file catalog/model/checkout/order.php on line 793 (or around there) I commented the line
Now I can receive mails but only as text.

That is exactly where I would look. Do you have an extension (OCMod or VQMod) that is sending the same email (HTML) to the admin that the customer receives?
That was my fix (I removed that extension) and now after 12 test orders... ALL came through.

Mike