If you want to send a specific E-Mail from your inbox to somebody else, use the Forward panel function for this purpose. Select the desired E-Mail and click on the forwarding function. This opens a window where you can enter the recipient. Follow the same procedure as during writing and sending of a new E-Mail.

As an alternative you can also activate the function Forward via the context menu.

If you want to forward several E-Mails at once, you can mark the wanted E-Mails and then click on Forward. The E-Mails are sent as attachments in a new E-Mail.