[VM] spam in vm

[Salome Södergran]

Hi!
I haven't yet come to understand how vm handles spam. By which
criteria, if any, does vm consider messages to be spam and what does
it by default do with such messages? Is there a way to make vm learn
about messages that I consider to be spam as does Thunderbird's junk-
protocol?
I haven't been seriously spammed in vm yet but I'd like to arm myself
in good time :-)
Best, Salome