Check whether is it a con email or not first. As far as I know, ASOS usually sends their parcels via normal mail / registered parcel and if you're supposed to pay for import tax, it should be handled by Pos Malaysia lo. Also, if those clothes are for own use, I think you shouldn't be taxed at all right? Not like they can say it's not for own use (unless you went and bought 10 of the same thing la hahaha)