Lately I have more and more occurrences when OR-generated emails end up in spam. I had several calls form renters saying they "did not receive" directions or door codes (which were sent on schedule). More often than not I ask them to look in spam folder and sure enough. They are there. I know nothing OR can do about spam settings but this makes SMS even more desirable.
You need to use our Verified Email system. That doesn't 100% solve this problem but it generally helps. Please reach out to the helpdesk for assistance in getting this set up.
I have had the same problem here recently. It seems to be with gmail accounts for me.