"Shop" means your business, whatever it is.
As joemike said, it's likely that one of your clients/customers/suppliers/???'s infected PC is being used to send out spam at your expense.
I hope your new passwords turn the trick for good.
Edit: I don't know how large your mailing list is, but would it be feasible to send out a blanket e-mail advising everyone on it to check their PCs for viruses (without getting busted for spamming, of course)?
Last edited by artie505; 08/03/14 09:07 PM.
