My experience is the same as yours. My understanding is that the 'send to' feature is primarily for sending email addresses to Thunderbird, not attachments. Others on the forum may have more information.

Hello, I have the following problem: let's say there is a Word file on the desktop, if I right-click on it and select Thunderbird in the "Send" item, the window for creating a message with this attached file does not open, but the document itself opens in Word. Can you tell me how to make the window of message creation with this attached file open?

In Windows, the usual process is to select 'Send to' in the file context menu and then 'Mail recipient'. This will open a new message in the default mail app with the file attached. It sometimes fails if other mail apps like Outlook are installed and are conflicting with TB being the default app. In that case, define TB as the default both in Windows settings and TB Settings/General/System Integration.

Yes, it works through the 'Mail recipient', but how can it be done specifically for Thunderbird. Everything worked fine before, but now it has stopped, I don’t know why.

In Windows, the usual process is to select 'Send to' in the file context menu and then 'Mail recipient'. This will open a new message in the default mail app with the file attached. It sometimes fails if other mail apps like Outlook are installed and are conflicting with TB being the default app. In that case, define TB as the default both in Windows settings and TB Settings/General/System Integration.

Yes, it works through the Addressee, but how can it be done specifically for Thunderbird. Everything worked fine before, but now it has stopped, I don’t know why.