How to disable XHTML-IM on Openfire?

Hi All,

I’m new on Openfire environment,

I want to shrink every message from Openfire,

because my client app didn’t read HTML message,

is it possible to disable XHTML-IM feature on Openfire?

specifically the XHTML-IM on Conference (MUC).

Is it accessible from Openfire Admin or we have to develop something like plugin?

Or maybe as the last option we have to rebuild the Openfire?

thank you for any help.