They appear to originate from one individual in a southern based design company, though they may also be an unwitting participant in the hack. Regardless we have brought the matter to the company's attention and asked them to cease and desist.
As far as we can tell, this is simply spam mail and not a virus, but we would advise you to delete those mails without opening.
We would also urge members to regularly review their own security settings as the Society receives several phishing, spam or virus containing mails from the membership each month.
Official mails from York Art Society are only sent from either a named Committee member or via the HTML formatted blog update from firstname.lastname@example.org