@kravietz @hal9000 OK I just did some testing too. When sending to an external email address the image tag is used to activate a URL call to the api.Criptext.com server (but no image is downloaded) if these two conditions exist: In your privacy settings you have read receipts set to ON and you send the email unencrypted (a normal email). So I believe @hal9000 is right that this method is used to maintain constant behavior. If however read receipts are turned off or you send the email encrypted..