I have a process where I'm sending a csv file via email. I set filename in UpdateAttribute and put there a polish letter, then I use PutEmail and send this file as an attachment, however on the receiving email the file name is messed up, it starts with '=UTF-8' and ends with '=', and not only that 1 letter is wrong but also '_' characters are replaced by '=5F'. When I don't use polish letter there are no problems.
This is my PutEmail configuration, it is set to UTF-8 which shouldn't have any problems with polish letters.
I use Nifi 1.20, earlier I was using 1.10 and this process worked flawlessly.