It is not possible to change the quotation introduction added when answering mail.
Andre Klapper
ak-47@gmx.net

# Changing the "On date, person wrote:" string when replying

Advanced users can change this string.

Open the dconf-editor application.

Navigate to `org.gnome.evolution.mail`.

Enter the prefered quotation string as the value for the key composer-message-attribution.

You might need to install the dconf-editor package to perform these steps.

Install dconf-editor