Hikashop NBG Pay Payment Plugin error

Hi,

First, please activate the debug setting of the Joomla configuration page and reproduce the error again.
This will display the full error message which will help us understand what's going on.

With the small error message "invalid address (from)" on your screenshot, it seems that the problem comes from the sending of an email where the sender email address is empty or invalid. In this case, the first thing to check is the "From address" setting under the "Emails" section of the HikaShop configuration page:
www.hikashop.com/support/documentation/5...fig.html#main_emails
If what is provided there is not a valid email address, it can produce the error message on your screenshot.

Note also that when you edit an email via the System>Emails menu, you have a "From address" input field which can override the setting from the HikaShop configuration for this particular email. So I would recommend you to check there too for the different order emails.
When you check the setting of the emails, please make sure you don't have a space in there. Normally, you're supposed to see the email address you entered in the configuration page in grey if the field is completely empty:
i.imgur.com/FGCDoE6.png
The fact that the error message ends with a ":" without anything after it could indicate that you've added a space in there.