CSF on Plesk 12 server

[zedoras]

We installed CSF on a Plesk 12 server (CentOS 6.5).
It seems to work fine, I can see in /var/log/lfd.log that it blocks IPs, but I don't receive any email.

I have set the LF_ALERT_TO parameter to my email address, and have enabled all email alerts in /etc/csf/csf.conf.
No logs are recorded in /var/log/maillog about CSF's outgoing emails!

Also, I had two servers with Plesk 11.5 and CSF, which were functional and were sending emails.
As soon as I upgraded them to Plesk 12, they also stopped sending emails.

I have tried to disable some new features of Plesk 12, like Fail2Ban, limitations on outgoing email messages, added 127.0.0.1 to mailserver's whitelist (open releay for localhost), but no difference.

Some other servers, which had apf firewall, are still sending emails, after upgrading them to Plesk 12.

[zedoras]

I found the solution.

Apparently in Plesk 12 sendmail cannot be used. It should send emails through Plesk's SMTP (postfix or qmail)
IP 127.0.0.1 should be added in white list (in Plesk -> Tools & Settings -> Mailserver Settings) and should be added to LF_ALERT_SMTP parameter of csf.conf:
LF_ALERT_SMTP = "127.0.0.1"

I restarted csf:
# csf -x
# csf -e

and then it started sending emails.

Also, in one case I should disable the:
'Switch on SPF spam protection'
in Mailserver Settings of Plesk, although the setting was:
'Only create Received-SPF headers, never block'