Squirrel shows the errors below:

Warning: session_start():
open(/tmp/sess_0b4a993815d68254606b8db69f89aebc, O_RDWR) failed: No space left on device (28) in /usr/local/cpanel/base/3rdparty/squirrelmail/functions/global.php on line 295

Warning: session_start(): Cannot send session cookie - headers already sent by (output started at
/usr/local/cpanel/base/3rdparty/squirrelmail/functions/global.php:295)
in /usr/local/cpanel/base/3rdparty/squirrelmail/functions/global.php
on line 295

Warning: session_start(): Cannot send session cache limiter - headers already sent (output started at
/usr/local/cpanel/base/3rdparty/squirrelmail/functions/global.php:295)
in /usr/local/cpanel/base/3rdparty/squirrelmail/functions/global.php
on line 295

Warning: Cannot modify header information - headers already sent by (output started at
/usr/local/cpanel/base/3rdparty/squirrelmail/functions/global.php:295)
in /usr/local/cpanel/base/3rdparty/squirrelmail/functions/i18n.php on line 280

Warning: Cannot modify header information - headers already sent by (output started at
/usr/local/cpanel/base/3rdparty/squirrelmail/functions/global.php:295)
in /usr/local/cpanel/base/3rdparty/squirrelmail/src/login.php on line 50

Warning: Cannot modify header information - headers already sent by (output started at
/usr/local/cpanel/base/3rdparty/squirrelmail/functions/global.php:295)
in
/usr/local/cpanel/base/3rdparty/squirrelmail/plugins/cpanel_auth/setup.php
on line 25

Horde shows:

Warning: Unknown(): open(/tmp/sess_2ae2cf9d8defe5c843a862febea078a6, O_RDWR) failed: No space left on device (28) in Unknown on line 0

Warning: Unknown(): Failed to write session data (files). Please verify that the current setting of session.save_path is correct (/tmp) in Unknown on line 0


And a domain has problems receiving emails (451 error). All is fine: dns zone, mx entry and email existience. No forwarders, filters or redirects setup nor spam assassin enabled. Did a test from MSN to the emial account and it didn't work. Did a test from MSN to another free email provider and got it there instantly.

Logged into root to reinstall exim and got this:

-bash-2.05b$ su -
Password:
/tmp/RsqUZPRg: No space left on device
root@server [~]# cd /tmp
root@server [/tmp]# dir

I did run /scripts/securetmp last night too. Could that cause it?

cPanel 9.9.9 R-14
Exim 4.x
RHE 3.3.

Server status all up

the email appearantly is stuck also when sending email.

An unknown error has occurred.

Server: 'mail.domain.com', Protocol: SMTP, Server Response: '451 Temporary local problem - please try later', Port: 25, Secure(SSL): No, Server Error: 451, Error Number: 0x800CCC6A


Why am I getting this error now?

I deleted some files from /tmp I don't know why it doesn't clear by itself.

Why 451 error?

You are out of free disk space in /tmp.

Remove some files and run tmpwatch as a cron job to have it cleaned up automatically.