Reply to a message by inserting the text from a text file

Hi everybody,
The other day I found codes to send a message with an attachment.
I create the macro and I am sending the message using a button. I love
it !
Now, I am looking for codes to reply to a message by inserting the text
from a text file.
I would select the message, and choose the macro depending on the text I
want to insert in the response.
In other word, I would select the message, press the macro button and
have the respond window open with the text in the text box. I don't want
the message to be send without having a look at it and sometimes add a
word or two. I would press the send button myself.
Something like that :
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Sub ReplyWinter()
From the select message open the RE window
Insert the text from Winter.txt
End sub
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Many thanks for your help,
Céline