for i in $(postqueue -p | grep -o -w -E '^[[:alnum:]]{11}'); do postcat -q $i | egrep '(Executable|Command)'; done 


Find originating scripts:
for i in $(postqueue -p | egrep -o -w '^[[:alnum:]]{10}'); do postcat -q $i | grep 'X-PHP-Originating-Script'; done |  cut -d':' -f1- | sort -b|uniq -c|sort -rnk1

for i in $(postqueue -p | grep '^[0-9A-Z]'| awk '{print $1}'); do postcat -q $i | grep 'X-PHP-Originating-Script'; done |  cut -d':' -f1- | sort -b|uniq -c|sort -rnk1

find 0/ -type f -exec grep -Ea -o Script\:\ [[:digit:]]+\:[[:alnum:]]+\.php {} \;|sort|uniq -c|sort -rnk1

Finding the size of the queue:
postqueue -p | grep -c '^[0-9A-Z]'

Check the file structure if the above command is taking too long:
ll /var/spool/postfix/active | wc -l


function _line { echo "=======Emails in $DIR Queue======="; };cd /var/spool/postfix;ls -l|egrep -o "deferred|hold|active|corrupt|defer|maildrop"|while read DIR; do _line; ls -lA $DIR|wc -l; echo; done;cd - 1>/dev/null;


egrep -o "\/var\/www\/vhosts[^:]*" /var/log/php_maillog|sort|uniq -c|sort -rnk1|head

Print the messages in the queue with the UID:
postqueue -p

Print the email message in the terminal:
postcat -q $UID

!!Clearing the queue!!
for i in $(postqueue -p | grep -o -w -E '^[[:alnum:]]{10}'); do postsuper -d $i; done

Forwarder location:
/var/qmail/mailnames/domain.tld/emailaddress/.qmail

Send email from command line:

echo -e "To:username@example.com \nSubject: Test mail from web\n\n Test mail from web via sendmail\n" | sendmail -t -F root@web.domain.com

"deferred - Mail that could not be delivered upon the first
    attempt. The queue manager implements exponential backoff by
doubling the time between delivery attempts."

"defer - Per-recipient status information about why mail is
   delayed. These files are maintained by the defer(8) daemon."