Oneliner to cleanup spool mails for each user in Linux

To delete all Linux spool emails for a user we should:

1. Switch to that user

   sudo su - username

2. Enter mailx:

   mailx

3. In mailx - issue:

   d*

   to delete all emails, and after that:

   q

   to quit

I've managed to create an oneliner that will do it for all users. Here it is:

for item in $(du -sh /var/spool/mail/*|grep M|sort -n|cut -f 5 -d\/); do sudo su - $item -c "echo 'd*'| mailx -N"; done