Yes, In Mailbox Receive operation mode the user sets up a filter in validation (match) memory for desired data that will be accepted into the mailbox matching the SDI+Label. The Receiver channel compares the SDI+Label of the incoming Arinc messages to the list of SDI+Labels in validation memory and if they match the incoming ARINC word (data) is stored in the Mailbox (RAM). Each ARINC channel has 1024 mailboxes, each addressed with a unique SDI+Label combination (SDI bits 8 and 9, Label bits 0 thru 7). Each mailbox only receives words containing its SDI+Label. Each mailbox is made up of 4 32-bit words (Status Word, Message, Timestamp and Match Enable). An ARINC mailbox cannot hold more than a single ARINC word at a time. In mailbox mode, the ARINC channel uses its Rx FIFO as a queue to hold SDI/Labels for which new messages have arrived. The user can poll the Rx FIFO count register then read the Rx FIFO to see which mailboxes have new messages.