Wedding planners and reps at a number of prominent wedding venues tell TMZ ... staff from the famed Biltmore Estate in Asheville, NC -- a backdrop in Macaulay Culkin's flick, "Richie Rich" -- contacted every couple that has a wedding scheduled at their venue over the next 8 weeks.

We're told the venue's urging couples to avoid gatherings of more than 50 people. So far, that's affected around 15 weddings, which were planned in 2019.

A rep for Biltmore Estate tells us ... they're allowing couples to postpone their weddings at their venue for up to one year from their current wedding date.

Another wedding planner tells us they've had 27 cancellations in just the last 3 days. They tell us some clients just stopped making payments and others have asked for a refund. We've called a number of wedding planners all over the country, and we're hearing the same story from all of them ... cancel, cancel, cancel, postpone, postpone, postpone.

As for those who want to tough it out and tie the knot, we're told some venues are offering closed-circuit viewing so friends and relatives can watch the ceremony without putting anyone at risk.

As for trying to cancel and get your money back, well ... that could be a problem. We've surveyed a number of insurance brokers. You CAN get wedding insurance, but until fairly recently it didn't cover outbreaks. Since the SARS and MERS epidemics, some insurance companies added a provision that said if a pandemic breaks out the bride and groom can cancel.

We're told insurance companies vary wildly when it comes to paying a wedding claim. One agent said the policy he writes would allow cancellation with a refund, but ONLY if the bride and/or groom test positive for coronavirus.