Hi there.
After months of trying to find out what was causing this issue, which included moving my website to a different server, using a sub-domain and many other tries, I discovered the issue was a forwarding one.
When forwarding is set on 301 (Permanent forwarding) my links work perfectly, but this means my IP address shows in the browser of those visiting, which is not ideal.
When forwarding is set to 302 (Temporary and Framed) my <a href="mailto: and < href=”SMS: links no longer work. The ‘Tab’ links to other URLs are ok. 302 (Temporary and Framed) now shows my website address which is preferred.
If I go direct to my IP address and bypass any type of forwarding, everything works fine. This indicates that it’s definitely a forwarding issue.
Now. THIS ONLY HAPPENS WITH iPHONES and iPADS. Yes I know this sounds impossible, but I’ve spent a long time proving it to be true.
Windows, Androids etc all work fine, so the issue is definately on Apple devices.