In Thunderbird, the 'Received' column shows the same date/time stamp as the 'Date' column. Some SMTP agents may delay sending immediately and release messages in bulk at certain later intervals than header 'Date' which is time written. In this case a message may not be 'received' until well after the send 'date' in the header. These times usually do not differ greatly but sometimes may be off by many minutes and could affect the way messages are ordered if sorted by 'Received'. Recommend a changed to Thunderbird where 'Received' column actually reflects the time shown in message header 'Received' or 'X-Received'.