Send order address from email error /failiure

-- url of the page with the problem -- : (sorry, no)
-- HikaShop version -- : 2.2.3
-- Joomla version -- : 2.5.17
-- PHP version -- : 5.3.10
-- Browser(s) name and version -- : Several different ones, all lastest, Safari, Firefox etc.
-- Error-message(debug-mod must be tuned on) -- : Error_message

Several orders today have been duplicated with one or serveral minutes in betwwen. Promting me to test the checkout process. I am logged in, place a item in the baske, check out and send the order. This last step takes a minute or two, but used to be much faster.

There is an error. This makes the customer place the order again, so there will be duplicate order.

I searched the swedish language files to find the exact variable. This is the one:

In my language: Swedish:
PHPMAILER_FROM_FAILED="Följande Från adress, misslyckades:"

In english:
PHPMAILER_FROM_FAILED="The following from address failed: "

Further down on the page, there is the usual confirmation that the order has been properly placed.

We are not aware of any changes on our server regarding email, or PHP, Hikashop (wellwe updated to latest, but the error occured in the previos version too), Joomla! (well we updated to latest) or on the SMTP-server. No changes in Joomla! settings regarding email.

Does this error have anything to do with Hikashop?