from Using FTP
To write larger files than the limit, the you (or your FTP client) must tell the server how large the incoming file is by giving the FTP ALLO command before the FTP STOR (put) command. Some clients may do this automatically. If your client does not, you can do this manually:

ftp> quote allo 123456789
200 ALLO command ok.
ftp> put bigfile write.test10
local: bigfile remote: write.test10
200 PORT command ok.
125 Data connection open; transfer starting.
226 Binary Transfer complete.
123456789 bytes sent in 23.547 secs (5.1e+04 Kbytes/sec)

Note:Once set, the size set with ALLO will remain in effect for that FTP session until you change it.