I have Ghost installed (and updated) on a Digital Ocean droplet, with Mailgun configured as per the guide documents, and running fine (emails go out to the subscribers like clockwork).
Completely by chance today I discovered that trying to subscribe to the blog via the “Subscribe” button in the top of the Casper (v.3.0.5, stock) theme that the modal subscribe form wasn’t working - but only for specific domains.
It seems the member sign-up function reports “Please enter a valid email address!” for outlook.com email addresses. I tried a variety of different common domains (yahoo, gmail, etc) - and they seem to work - only outlook does not.
Any ideas what’s going on ? I’ve searched other community posts, and there are a few similar sounding reports, but nothing exactly the same.