Right Click to create new message.

[Yunis_waqa]

This used to exist in the old version of Thunderbird, when you right clicked on inbox you could create new message. Now that does not exist, you have to use keyboard shortcut  (Ctrl+N)  or use the menu File -> New Message

[Jon]

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[Agentvirtuel]

Hello

Which version?

And, "New message" button ?
https://support.mozilla.org/en-US/questions/1521809

[siffemcon]

Yeah, which version? That option doesn't exist even in TB v102.