This program can be integrated into Claws-Mail to transfer a mail to a ToDo.txt item with a link back to the original mail. By default it will use the Subject of the mail as task description. If you start the program with the parameter "-i" it will ask you for a task description and only fall back to the mail subject if no description is given.
To add the program to Claws-Mail go to Configuration->Actions... and create a action which executes following command:
/path_to_mail2todotxt/mail2todotxt.py -i %f &
Now you can create a task for the selected mail by calling Tools->Actions-><The_name_you_chose_for_the_action>. Additionally Claws-Mail also allows you to create a short-cut to execute the action.
To go back from the ToDo.txt item to the mail you need this ToDo.txt extensions.