OTRS provides basic text signatures, which really aren’t great. So here’s how to enable HTML signatures in OTRS:
Edit the following file using Nano:
sudo nano /opt/otrs/var/httpd/htdocs/js/Core.UI.RichTextEditor.js
Search for **extraAllowedContent **by pressing CTRL+W and add img to the list of allowed HTML tags. Save the file by pressing CTRL+O and exit Nano by pressing CTRL+X.