ls -l /var/ | grep mail

lrwxrwxrwx.  1 root root   10 May 16  2022 mail -> spool/mail

ls -l /var/spool/ | grep mail

drwxrwxr-x. 3 mail  mail  26 Jan 23 10:11 mail

ls -l /var/spool/ | grep exim

drwxr-x---  5 exim  exim  68 Jan  4 00:05 exim

exim -bP | grep exim_user

exim_user = exim

id exim

uid=93(exim) gid=93(exim) groups=93(exim),12(mail)