Es handelt sich um ein Verhalten, das von Debain ausgelöst wird. Installiert man folgende Erweiterung, wird das Icon angezeigt:
When establishing a connection via the Connection Manager, the message “No reply message received” displays. Please check the host name and ensure that you only use valid characters (RFC 952):

. (dot)
- (hyphen)
When sending documents through ecoDMS, only one email window opens without attachments. Microsoft Outlook for Mac does not support this function.
During various graphical operations (e.g. using the clipboard) ecoDMS Client may shut down.

This is not an ecoDMS error but a Qt bug:

Read Bugreport

As a workaround you can install alternative NVidia drivers:

Installation Guide

AYou must restart ecoDMS Client afterwards.
A bug prevents sending documents directly from ecoDMS with Thunderbird under MacOS. Mozilla.has been notified.

The email which opens displays the following instead:

"Sorry, unable to add attachment(s). Thunderbird does not support attachments on MacOS."