==== REQUIRED BASIC INFO OF YOUR IREDMAIL SERVER ====
- iRedMail version (check /etc/iredmail-release): 0.9.8
- Deployed with iRedMail Easy or the downloadable installer? installer
- Linux/BSD distribution name and version: ubuntu 16.04
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): mysql
- Web server (Apache or Nginx):nginx
- Manage mail accounts with iRedAdmin-Pro?no
- [IMPORTANT] Related original log or error message is required if you're experiencing an issue.
====

So I read a forum post from several years back about deleting large amounts of emails from the server.
It seemed to indicate where all the mail is stored.
From the post:
-----------------------------------------------------------------
I'm not sure if this is what you're looking for but all the actual emails are locate in
/var/vmail/vmail1/<domain>/<username>/Maildir/cur
/var/vmail/vmail1/<domain>/<username>/Maildir/.Drafts
/var/vmail/vmail1/<domain>/<username>/Maildir/.Junk
/var/vmail/vmail1/<domain>/<username>/Maildir/.Junk E-mail
/var/vmail/vmail1/<domain>/<username>/Maildir/new
/var/vmail/vmail1/<domain>/<username>/Maildir/.Sent
---------------------------------------------------------------------

But on my server I am seeing single-letter directories!

root@eml3host:/var/vmail/vmail1/eml3.causeaction.com/b/o/u# ls
bounceeml1-2019.01.15.03.13.00  bounceeml2-2019.01.15.03.13.59  bounceired-2019.01.15.03.09.15  bouncemlr1-2019.01.15.03.10.49  bouncemlr2-2019.01.15.03.11.44

what is the b and o and u all about??? And then the strange dated folders.
And inside those Maildair and dovecot folders.
Man I have no idea what to do with this.
Not nearly as easy as the old forum post said it would be.

Thanks for any help.