set language of post

hi,

i use ceceppa multilanguage plug-in,
when I create a new post I must also indicate the language,
otherwise the post will not be displayed.

The plug-in provides the bees, http://www.alessandrosenese.eu/en/ceceppa-multilingua/api

how do I specify which language to use when creating the post by email?
thanks

https://wordpress.org/plugins/post-by-email/