Welcome to the Community, @kevinhart-optusn.
You can advise your customer to open the email using an incognito mode. Encountering errors when accessing websites can be sometimes caused by a piled-up stored cache and cookies on your browser. Private mode prevents storing cache and web history to avoid issues when running websites. Below are the shortcut keys they can use:
- Google Chrome: press Ctrl + Shift + N
- Mozilla Firefox: press Ctrl + Shift + P
- Microsoft Edge: press Ctrl + Shift + P
- Safari: press Command + Shift + N
If it works, they have to clear their browser's cache to have a clean slate. If not, I recommend using another supported browser.
Meanwhile, QBSE has a set of tutorials to help you with your navigation. To start, simply click whichever category you'll want to open.
Feel free to post here again if you have further concerns about accessing your emails. I'm just a post away to help. Keep safe.