INET MU allows you to mark trustworthy emails so that you can be sure that they are not fake in the future. Simply set your own mark in the system settings, which will be used to mark emails from INET. This mark will always appear in the message header as proof that the email actually came from the INET MU system.
To set up the label, simply log in to INET MU and go to the Settings using the link in the top bar (gear icon).
Then fill in the fields in the Anti-phishing email section. You can enter your own text and insert icons there. In short, you can create your own unique mark. Then save it, and every subsequent email from INET MU will contain this mark (see image). This will allow you to recognize that the message actually came from this system and is not a fake.