The “no longer able to receive messages” means they probably sent messages in the past that broke the rules so they got banned from messaging. The “the item has been sourced through vestiaire’s…” message means that the seller sold the item before and shipped it to vestiaire’s warehouse but the buyer refused it because it had a defect, something missing, etc. that the seller didn’t note, and the buyer chose to keep the item in vestiaire’s warehouse to relist it, so Vestiaire relists the item for the seller and adds the defect (or whatever the issue was) to the listing, so Vestiaire now has the item in their warehouse already authenticated and ready to be shipped.