Unread emails. Even when I'm offering work!

Many will know that my house/studio is being sold and while it has been emptied I've done a couple of unscheduled shoots and allowed others to use the space. I have arranged a 'farewell' shoot with a model who has done many shoots with me, and I wanted to make it a g/g shoot. All very tasteful and soft, but using the backdrops now available in a bare house with lots of natural light, and so on.
I have contacted several models that I feel will complement the shoot but, to my surprise, I have not even received the courtesy of a reply.
My images are there for all to see and I feel that they are of a sufficient standard to use in a portfolio. Beyond that, I am paying. It's a real job. I would at least expect to get a 'sorry no', but no reply is a bit much.
I have also looked at my sent emails and see that some remain unread. Why can this be?
Anyway, the house is mine for a few more weeks and is available for use by anyone who wants space.
After that I'll be setting up on the edge of Exmoor in a beautiful bucolic location with a stream, woods and all the trappings of nature.