GPRS Send mail with attachment file on SD card

Hello!
There is a problem I can't send a file from SD card by email (sim800)
if you create a command AT+FSCREATE=RFIDlog.csv
and attach it to the email AT+SMTPFILE=1,"RFIDlog.csv",0
it's all good, but if the file is on the SD card, I can't attach it
tell me how to copy a file located on the SD card with memory modem (Sim800)?