Is it possible to publish a webservice for receiving request attachments in Mendix 7.23.6 ? (MTOM)
I know this is possible using a REST service.
Yes, this should be possible. You can take a look on the app store. There is demo app to handel REST services.
Calling (SOAP) web services from Mendix using MTOM is supported for sure, but last time I checked publishing them was not.
Not entirely sure if this was later added in a more recent version of Mendix, but I don’t think so.