Plesk 12.x / Linux :: Postfix - Mails Sent Through Sendmail Binary Blocked Because Of Wrong HELO

My server is using Centos 6.5... I updated from Plesk 11.5 to 12 last week and postfix to 2.8.17.

Since then, all mails sent using the sendmail binary (notifications, mail forwards...) are being rejected with a wrong HELO hostname: localhost.

It seems that sendmail is using locahost as a HELO tag which is not accepted. Here is the following error:

Code:

Jun 23 14:23:20 ns395167 plesk sendmail[29817]: handlers_stderr: SKIP
Jun 23 14:23:20 ns395167 plesk sendmail[29817]: SKIP during call 'check-quota' handler
Jun 23 14:23:20 ns395167 postfix/pickup[29480]: B94BC6AA20A6: uid=0 from=<root@curuba.fr>
Jun 23 14:23:20 ns395167 postfix/cleanup[29507]: B94BC6AA20A6: message-id=<20140623122320.B94BC6AA20A6@ns395167.ip-176-31-117.eu>

[Code] .....

Here is my postconf -n content:

Code:

alias_database = hash:/etc/aliases
alias_maps = hash:/etc/aliases, hash:/var/spool/postfix/plesk/aliases
command_directory = /usr/sbin
config_directory = /etc/postfix
daemon_directory = /usr/libexec/postfix

[code] .....

My system hostname seems correct:

Code:
hostname -f
ns395167.ip-176-31-117.eu
hostname
ns395167.ip-176-31-117.eu