Exim mail delivery issue after upgrade URGENT

Following a recent cPanel/Exim upgrade, Exim is unable to deliver or inspect queued messages even though the corresponding spool files physically exist.

The server uses MailScanner/CSF and separate incoming/outgoing Exim configurations.

Configuration

Default Exim:

spool_directory = /var/spool/exim_incoming
split_spool_directory = yes

Outgoing Exim:

/usr/sbin/exim -C /etc/exim_outgoing.conf -bP spool_directory
spool_directory = /var/spool/exim

/etc/exim_outgoing.conf also has:

split_spool_directory = yes

MailScanner is configured with:

Incoming Queue Dir = /var/spool/exim_incoming/input/*
Sendmail2 = /usr/sbin/exim -C /etc/exim_outgoing.conf
Split Exim Spool = yes

Symptom

Messages remain in the outgoing queue indefinitely.

For example:

1x52kp-0000000EzHV-0BXO

appears in:

/usr/sbin/exim -C /etc/exim_outgoing.conf -bp

but attempting to inspect or manually deliver it fails:

/usr/sbin/exim -C /etc/exim_outgoing.conf -Mvh 1x52kp-0000000EzHV-0BXO

Failed to open input file for 1x52kp-0000000EzHV-0BXO-H: No such file or directory

Likewise:

/usr/sbin/exim -C /etc/exim_outgoing.conf -M 1x52kp-0000000EzHV-0BXO

results in:

Spool file 1x52kp-0000000EzHV-0BXO-D not found

However, the files physically exist:

/var/spool/exim/input/0/1x52kp-0000000EzHV-0BXO-H
/var/spool/exim/input/0/1x52kp-0000000EzHV-0BXO-D

with appropriate ownership:

mailnull:mail

and permissions:

0750

The same behaviour occurs with multiple unrelated queued messages.

A forced queue run:

/usr/sbin/exim -C /etc/exim_outgoing.conf -qff

sees the messages and reports:

delivering 1x52kp-0000000EzHV-0BXO

but the messages remain in the queue.

Additional evidence

The Exim log shows the original message being received successfully, followed immediately by an attempted -Mc operation reporting the data spool file missing:

2026-09-12 01:01:27 1x52kp-0000000EzHV-0BXO <= email@gmail.com ...
2026-09-12 01:01:31 cwd=/var/spool/exim/input 5 args: /usr/sbin/exim -C /etc/exim_outgoing.conf -Mc 1x52kp-0000000EzHV-0BXO
2026-09-12 01:01:31 1x52kp-0000000EzHV-0BXO Spool file 1x52kp-0000000EzHV-0BXO-D not found

The physical -H and -D files are nevertheless present in /var/spool/exim/input/0/.

The installed Exim package is:

cpanel-exim-4.100-1.cp130~el8.x86_64

and:

Exim version 4.100 #2 built 10-Sep-2026 09:30:16

rpm -V does not report /usr/sbin/exim as modified.

Request

Please advise on the correct cPanel-supported configuration/recovery procedure for this Exim/MailScanner split-spool setup.

Specifically, we need to determine why Exim's outgoing instance can see the queue entries and physically present split-spool files, but cannot resolve those files when processing -M, -Mvh, or queue delivery.

There are currently queued emails that need to be delivered, so we do not want to delete or recreate the queue until the correct recovery procedure is confirmed.