Emails withWix site links not being received

So, here’s an odd one. When I am developing a site for a client, I send them the link to the site under development so they can comment. I’ve recently found that any email I send with a link to a Wix Studio demo site marks as sent in my email program, but is not received by the recipient. I’ve tested this with a couple of variables, (sent from my phone not wifi, got my wife to try and send the link to me, used the email online rather than via the app). All to no avail. It’s quite concerning as letting the client see my work is a bit fundamental. Anyone got any thoughts?
Best wishes,
Nick