Hello Sébastien,
Just this morning I found the solution, at least for what I need to do:
The proper format for inserting into the 3rd-party mapping form is indeed the short name of the checkbox element, such as checkbox-301
Like you discovered, the array was not being accepted by SugarCRM. In order to send just a simple string instead of an array, I changed the checkbox element in CF7 to “exclusive”, that is, only a single choice is permitted.
In the CF7 definition of the checkbox named “checkbox-301”, it is, for example:
[checkbox* checkbox-301 exclusive “Schedule a meeting” “Schedule a live demo” “Set up test account” “Discuss partner opportunities”]
In the 3rd-party mapping, it is only identified by: checkbox-301
Now it sends only the simple string, the single answer, and posts correctly to SugarCRM.
I hope this helps. Regards. Ray