This is happening on two computers both running Win 10 64. Historically when an email is received the text for that listing when viewing the inbox is bold. This changes to normal when the email is read. Sometime over the last couple of days to the text is normal on receipt of the email and when read There is therefore no distinguishing feature on the inbox listing between the emails that have been read and those that haven't. Since this has happened on two separate machines using several different email addresses, I'm assuming that something must have changed with Thunderbird. Comments please. Thanks Peter