parents in laws visa rejected twice

[vishwa]

hi!
my parents in laws v.visa has been rejected twice in interview in last month.
and at second time counslate give them reason and note which is similar to following statment(as i don't know exact statement)
"you can not apply personally for 2 years, can apply through mail ."
can you guide me what it means?how they can apply though post?or they can not apply at all for 2 years?
thanks
vishwa

[immihelp]

Rule has changed recently in which you can apply as many times as you want.

Go to https://www.immihelp.com/usa-visas/visitor read about Refusal.