Hello there We have read the message We try to help

Can you send me a screen shot? https://support.mozilla.org/en-US/kb/how-to-make-screenshots

Greetings Firefox volunteer

Sorry, I didn't look properly. In fact the problem is that I have two of the 28th February (Wednesday & Thursday), then Friday the 29th Feb, and then Saturday is correctly 2nd March.

Please offer a bit more info.

What OS are you using? What version of Thunderbird are you using? What language are you using eg: en-GB is English British ?

Where did you get the download of Thunderbird? Did you get it from the official webpage: https://www.thunderbird.net/en-US/thunderbird/all/

Or from a microsoft app or flatpack etc ?

Thanks for replying. I've just updated Thunderbird and the problem has been fixed.