File->Send File ignores XON/XOFF
Please refer to below page.
http://ttssh2.sourceforge.jp/manual/en/menu/setup-serialport.html
I don't use XMODEM nor any other protocol. I don't use File->Transfer->...., I use File->Send file, then I check "binary" and blindly send the file. The device is already prepared to receive it and sends XON/XOFF when necessary. But the TeraTerm does not stop.
I connect to an external device using serial port. I have enabled XON/XOFF flow control in serial port parameters. I send the file using File->Send File menu. The device sometimes is slow and then it sends XOFF (I'm sure it does, XOFF is in TeraTerm log). TeraTerm keeps sending data and ignores the XOFF command so data is lost.