Install qmail-remove, and remove spam with calling:
qmail-remove -r -p 'your-keyword'
1. stop qmail service
systemctl stop qmail.service
2. check your queue with:
/var/qmail/bin/qmail-qstat
3. read I found out who is sending who, and what
/var/qmail/bin/qmail-qread
Then use qmail-remove with your selected keyword.
How to install qmail-remove?
# cd /tmp
# wget
http://www.linuxmagic.com/opensource/qmail/qmail-remove/qmail-remove-0.95.tar.gz# tar -zxvf qmail-remove-0.95.tar.gz
# cd qmail-remove-0.95
# make && make install
# ln -s /usr/local/sbin/qmail-remove /usr/bin/qmail-remove
# mkdir -p /var/qmail/queue/yanked/