Our default theme for e-mail notifications includes XTRF signs and "Powered by XTRF" pictures. So, all e-mails that go out from the system contain them.
You can reduce the XTRF branding or remove it altogether in all outgoing e-mails by creating your own theme.
Go to Templates > Notifications > Themes in the system configuration and either edit an existing theme from the list to your liking, or add a new one from scratch.
If you replace XTRF graphics with your own, pictures need to be uploaded in the E-mail Images tab. Click the Preview button at the bottom of the screen to see how your changes will look after they are saved. The following article may also be helpful: https://xtrf.userecho.com/knowledge-bases/6/articles/123-how-to-insert-an-image-into-an-e-mail-notification-template
Your visual identification can be added to portal login pages too - see https://xtrf.userecho.com/knowledge-bases/6/articles/162-how-do-i-change-the-login-page-logo-to-my-companys
Customer support service by UserEcho