Keeps trying to send undeliverable message at launch

[SaulYago]

Hello,
I'm getting a "Send Message Error" for a message I scheduled because the destination address no longer exists.
The message never appeared in the 'Send Later' folder, so I can't locate it.
Every time Thunderbird is launched, several attempts are made to deliver the message.
Uninstalling the plugin did not help.
Searching for offending email address across hard drive does not produce any results.
I need to know which file I need to modify/delete so I do not have to do a complete reinstall of Thunderbird.
I'd be extremely grateful for any pointers.

[jikamens]

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