Hi, it seems that the issue reported here is still happening. That thread mentions a fix coming in 1.1-3, but 1.1-2 is still the most recent package available for me.
But, also, that means you’ve disabled or deleted the Virtualmin repo config, because I rolled the fix to all repos, I’m pretty sure, including the ones that are now long deprecated and unmaintained.
Those are deprecated, but I thought I’d pushed the procmail-wrapper update to them, anyway…but, you can just grab the package from a newer repo. It’s the same.
The /vm/6 repos are still maintained, so you can switch the universal repo over to using that, if you want. But, xenial is getting no more updates from upstream, so it’s dangerous to run it, no matter how stable it’s been. You have a handful of unpatched security issues in your Apache and probably other services.