@salixlucida It's not the surface-to-surface transmission that concerns me (although, licking envelopes...) It's the way you have to get closer to people to hand them a card, plus navigating crowded streets where people don't mask up, to get to the postbox. Nevertheless, that study is reassuring.
Covid adjacent, but what isn't these days?
@rosjackson
There are scant evidences supporting that concern, despite the media hype earlier this year.
If you're still worried you can buy one of those ultraviolet contraptions online, which is also useful for other purposes.