scanning exim frozen mails for spam

I had a bunch of frozen emails. I wanted to be sure there was no spam. I did this command:

exim -bp | awk '{if ($3!="") {print "newMessage"; system("exim -Mvb " $3) } }' | awk 'BEGIN{RS="newMessage"} !/different string|I do not want|to include inside|mails/{print $0}' | less

So I ignore mails containing certain words and remain only with those strange mails.

I discovered I had sent no spam, but instead I had received undeliverable mail which mas kept frozen.