Quite frequently we see this type of thing happen if someone has added their own email address to the allow list, so I took a look at the welcome list
for your account and see that your email address is
in the list.
There's a good chance our system did flag this as spam, but allowed it through because of that entry.
These days, there's no need to have your own address in that list as anything you actually send to yourself will be delivered, but it does allow for these types of spoofed messages to make it through when they often would not.
I'd be happy to remove the entry for you if you'd like, or you can do so using the link above.
Thanks for posting about the issue. Have a wonderful weekend!