Anonymous vsftpd and upload only
Maybe you want to allow anonymous users to upload files, but, not being able to delete the content afterwards ? Here is a config that seems to be working for the purpose for vsftpd v 3.0.2 on a RedHat7 at least.
anonymous_enable=YES anon_root=/var/ftp/pub write_enable=YES anon_mkdir_write_enable=YES # anon_other_write_enable=YES does mean that users CAN delete content. anon_other_write_enable=NO anon_upload_enable=YES anon_world_readable_only=NO anon_umask=002 chown_upload_mode=0660 local_enable=NO chroot_local_user=NO chroot_list_enable=NO guest_enable=YES guest_username=ftp chown_uploads=YES chown_username=ftp dirmessage_enable=YES xferlog_enable=YES connect_from_port_20=YES xferlog_std_format=YES listen=YES listen_ipv6=NO pam_service_name=vsftpd userlist_enable=YES tcp_wrappers=YES