It's really hard to say why you are blocked on Poshmark. I'm in the UK so can't use this site as they don't ship internationally, therefore I have no personal experience so anything I say to you here is just other people's opinion.
Several people claim to have been blocked 'for no reason' though I guess Poshmark must have their reasons. Some people have said that Poshmark won't give them a reason - I don't know how true this is but I would think that they owe their members an explanation at least.
Have you tried contacting them to ask the reason? Maybe you violated one of their terms without realising. If that is the case they may reinstate you if you apologise and explain that you were unaware of that particular rule.
I hope you can get this worked out, it must be very frustrating for you.
