Xargs: multiple commands to each argument

Hello. There is my one-liner to get subjects of potential spam mails

sudo exiqgrep -bf "spamer@example.com" |cut -d' ' -f1 |xargs -I ~ sudo /usr/sbin/exim -Mvh ~ |grep 'Subject: '

I want to insert blank line after each iteration to make output more readable. I tried

sudo exiqgrep -bf "spamer@example.com" |cut -d' ' -f1 |xargs -I ~ sudo /usr/sbin/exim -Mvh ~ |grep 'Subject: ' && echo ""
sudo exiqgrep -bf "spamer@example.com" |cut -d' ' -f1 |xargs -I ~ echo "" && sudo /usr/sbin/exim -Mvh ~ |grep 'Subject: '
sudo exiqgrep -bf "spamer@example.com" |cut -d' ' -f1 |xargs -I ~ sh -c "echo \"\"; sudo /usr/sbin/exim -Mvh ~ |grep 'Subject: '"

Please advice.

Instead of grep, you can use awk?

I mean instead of

grep 'Subject: '

use

awk '/Subject: / {print $0"\n"}'