The Main Reason for this error to show up is because you are probably using an email which does not use the website’s domain. So all you would need to do in this case is:
Access The Joomla Administrative Backend, click “Site” on the menu bar, and select “Global Configuration“.
On the right hand side, you should have a form box, fill in as below:
Make sure that the email address uses your domain name. Lets say your website is http://www.hello.com , than in that case a good email would be firstname.lastname@example.org! The email does not need to necessarily exist, it will still work.
In some cases some changes to the settings in the ftp file are also required. In that case, log in to the ftp account.
Copy and paste the link below in the url bar after your domain name: youDomainName/administrator/components/com_virtuemart/classes/
Open the file sp_main.php in a notepad. (make a copy just in case)
find the line: $mail->Sender = $from ? $from : $mosConfig_mailfrom;
Delete it and paste the following line instead: $mail->Sender = $mosConfig_mailfrom;