The EICAR test virus is a component of Avira Exchange software. It is used, for example, to test the engine of the System Scanner. If the local virus scanner points out this file and reports a detection, you have to configure Real-Time Protection (Guard).
Please open the configuration GUI of the Avira Antivirus Server and go to PC Security → Exceptions. Add the following exception to "Files and folders to be ignored by the system scanner and real-time scanner".
Avira Exchange Security OEM:
C:\Program Files\Avira\Avira Exchange Security\
Avira Exchange Security SBE:
C:\Program Files\Avira\Exchange Security SBE\
Real-Time Protection will then stop scanning this directory and reporting the EICAR test virus.