Delivered-To: GMX delivery to <my visible email address>
My visible and easily remembered email address is redirected to my ISP email by another system, and I see this system says
All incoming and outgoing e-mails including their file attachments are automatically scanned for viruses using Symantec's superior and powerful anti-virus scan engine
so I'm guessing Symantec is somehow related to GMX.
Not really related, it is just that the e-mail service provider [GMX, Global Mail Exchange] have decided to use Symantec's anti-malware software.
By the way in case anyone hasn't realised, the headers are in reverse order so as you read down them you are tracing the message path back form your mail server to the mail server of the sender