I'm writing to you from a school in Scotland. When we try to email any of our parents that have a Virgin Media domain email address (blueyonder.co.uk,virgin.net etc.), we get; 554 5.2.0 Spam content found via a bounce back email.
Firstly please accept my apologies for the current issues you've reported. It's highly likely that the bounce backs are due to misconfigured DNS settings on your platform - a factor that wouldn't have made any difference a few months back but which can result in a hard fail from us as part of the spam limiting measures we've deployed.
I'd like to see the Header data for one of your failed sent mails please with a view to getting this escalated to our Postmaster.
I do appreciate how much of an inconvenience this is for you and am eager to get this resolved as quickly as possible. Please reply to my PM (purple envelope icon, top right of page) when you can and I'll get this matter progressed.