Unfortunately Avast FTP server seems to be broken...
Downloads$ ftp ftp.avast.com
Connected to ftp.avast.com.
220 Welcome on ftp.avast.com.
Name (ftp.avast.com:matthias): anonymous
331 Please specify the password.
Password:
230 Login successful.
Remote system type is UNIX.
Using binary mode to transfer files.
ftp> cd incoming
250 Directory successfully changed.
ftp> put myname@mycompany.com.zip
421 Service not available, remote server has closed connection
ftp: No control connection for command