Invalid mailbox syntax is used – special characters

Hello CF7!
So I have an issue with providing my email in the “from”-box. I have specified the syntax as advised in the docs but I get the error anyway. I assume this has something to do with me handling a Swedish domain with special characters.

Example of syntax (the domain is something else but with same special character used):
B?st <info@b?st.se>

Any help and suggestions to what might be causing the problem would be much appreciated!