Daniel @miconda please look this [textops](https://www.kamailio.org/docs/modules/5.2.x/modules/textops.html#textops.f.s...) doc page Here is present usage example: ``` set_body_multipart("test", "text/plain", "delimiter"); msg_apply_changes(); append_body_part(...); ``` first two comands 1) convert body to multipart; 2) add payload with content type text/plain.
I have [tested this two commands](https://github.com/kamailio/kamailio/issues/1719#issuecomment-437619001). And this not produce valid body.