SMTP server response: 503 This mail server requires authenti

When trying to send an email from our 'newly installed' online store (Version 2.1.0.1) via a script I am receiving the following error message

"SMTP server response: 503 This mail server requires authentication when attempting to send to a non-local e-mail address. "

The contact form within the online store works with the settings I have in place which I presume is because the email is being sent to sales@our store.com which is a local address.
The issue seems to be when trying to send emails out from the server to other addresses

Is this a setting on the server itself that needs adjusting or something within the Opencart files/settings?



Many thanks,


Edit: The full error message is below...

SyntaxError: JSON.parse: unexpected character at line 1 column 1 of the JSON data

OK

<b>Warning</b>: mail(): SMTP server response: 503 This mail server requires authentication when attempting to send to a non-local e-mail address. Please check your mail client settings or contact your administrator to verify that the domain or address is defined for this server. in <b>C:Inetpubvhostsour_store.comhttpdocsstoresystemlibrarymail.php</b> on line <b>164</b>[]

This is now fixed and if anyone else has the same problem it is related to Opencart software not working correctly with SMTP

To fix this issue do the following:

Install VQMOD for Opencart:
http://www.opencart.com/index.php?route ... n_id=19501

Then follow the instructions here:
https://github.com/vqmod/vqmod/wiki/Ins ... n-OpenCart
(pay attention to the folder/file permissions - the Youtube video explains very well)

Then install this free extension:
http://www.opencart.com/index.php?route ... earch=smtp
(it works also for Opencart version 2.1.0.1)


Got to your admin >System>Settings> open your store> Mail

Change the settings to:

Mail Protocol:SMTP
Mail parameters : leave blank
SMTP Hostname: your SMTP host name eg: yourdomain.com
SMTP Username: eg mailbox@yourdomain.com
SMTP Password: your SMTP password
SMTP Port: eg 25
Timeout: eg 5

And then test your Contact us form and 'Notify customer' when editing orders

Usually when it requires authentication while using "MAIL" and not SMTP, you can do the in the mail params. Note the -f and NO space

Reference: http://php.net/manual/en/function.mail.php