Hi @outlander, @s-jay, @Former-Member. Not sure if this relates to the issue, but a while back the same thing was happening with all email notifications. The site was showing up in the address bar as 'secure' with the padlock icon when members came to the site by typing in the SANE address. But when going to any posts from email notifications, the site was showing as 'not secure'. Turned out it was something to do with links in notifications being in the http:// format, rather than the https:// format.
Edit: for some reason, when I received an email notification about this post, it translated the http mentioned above, into https. Looked like I had said something quite meaningless! I'm guessing that was a automated security edit before email notifications were sent. Hope this makes sense. If not, make sure you read the message on the site itself, rather than in email notifications. 