That started happening to me a week or so ago and I discovered that the auto emails from RRB are now coming in with the "inquiry@ratrodbikes.com" email address. If you look in your Junk Mail box, you will probably see the emails there. All you have to do is find the section in your email program of choice that allows you to "whitelist" email address and add the inquiry@ratrodbikes.com address there.
They could still be getting blocked. Try adding that email address to your whitelist. It worked for me.
This is always an issue due to the email account that I use for the forum getting maxed out each month. The quantity of emails that come through the system end up blowing up the gmail set up that I'm using. I need to find a better email solution to use for the site.
...and for me, having an old computer, an old operating system, and search engines that are no longer supported, is the other side of that problem.