I have the option "Job Recommendations - Upwork has job recommendations for me - daily" set in my email notification preferences but I NEVER receive any emails about new job postings. I asked about this a long time ago and was told it was being fixed.
Back in October 2018 Amanda said, "We are not currently sending email notifications of new job postings, as there was an issue with the notifications, that should be restarted soon, and all Freelancers will be notified when that is restarted. "
Are they EVER going to fix this? If they are not going to fix it suggest they remove the option from the menu.
I really don't expect it to get fixed, so I wouldn't hold your breath. Honestly, I don't think those emails would be very useful, because it takes the same amount of time to check an email for new job postings as it would to just check your Upwork dashboard.