FTP with backslash in username or passwd

If you have a backslash in username or passwd, you need to do a special character to escape backslash.

For example: ftp\username

export ftpusername='ftp\\username'

If you put a double quote around export ftpusername, it doesn't work. Or if you try to add "/" like "ftp/\username" doesn't work either. Imagine how syntax could get your way.