You may create/change a signature in the Horde WebMail following the steps given below:

  1. In the icon bar at the top of any mail page in the Horde WebMail, click on the Options icon.
  2. In the Your Information column, click Personal Information.
  3. On the Personal Information page, click Edit your identities.
  4. Select Default identity from the Your identities pop-up menu, type your signature text, and click the Create button.
  5. Confirmation that the change you have made to your default identity -- adding a signature file -- has been made will appear at the top of your window.