Add caution text to incoming mail

NethServer Version: NethServer release 7.7.1908 (final)
Module: your_module
I want to add the following text in every incoming mail in my production box…

External Email . Treat hyperlinks and attachments in this email with caution.
Help me to get this done

Look after nethserver-mail-disclaimer IIRC

Hi stephdl,
My question is about adding a alert message for the incoming mails but not the outgoing mails.
Disclaimer we can always set through GUI.
Hope am clear in asking

Sure we have not implemented it, but from the smtp point of view incoming/outcoming emails are the same.

I think rspamd could do it like altermime.

Hi
How could I do it in rspamd?

This is the issue which has introduced it, I let you dig in the documentation