Can anybody help me with code?
It will be usefull for all others users.
Is it possible to rename the incoming files with first word in message delimited with space.
Example: incoming_date.txt renaming to word_date.txt
"word" represent the incoming messages body with: "word Hello I am..."
It is usefull to filter incoming messages for diferent users on one number.

I do not provide a code, because I do not know what language you like to use, and have used before.

It is possible to rename the incoming message file, this can be easily done in the eventhandler script. If you want that the name of a file starts with the first word of a message, eventhandler is the only option for this.

Are you currently using any eventhandler script, for example like shown in this answer?

That script already extracts the first word, but if it's used for renaming, illegal characters should be changed before using it as a part of a filename.

There is also a configuration setting filename_preview available, is it out of scope for you?