You can choose the additional options while sending an email:
Encryption - You can encrypt your email by clicking on the lock symbol. (Please note that if you are in Automatic Encryption Mode, your email will be automatically encrypted) Check this link for more information regarding Encryption in Canary.
Formatting - The formatting option allows you to style your message body in Canary. Check this link to know more about styling Text in Canary.
Attachment - You can attach PDFs, photos, documents etc. via the attach symbol. Check this link to know more on how to attach file/s in Canary.
Templates - The Template Symbol allows you to add templates. Check this link on how to use Templates in Canary.