Issue Problem "Mail server CPU usage"

[bonny3]

Goodmorning everyone,
I have a problem with the "Mail server CPU usage", it always ranges from 60% to 90%
I have a dedicated Intel® Xeon® E5-1650 v3 Hexa-Core Haswell server
incl. Hyper-Threading-Technologie 256 GB DDR4 ECC RAM 2 x 480 GB SATA 6 Gb / s SSD.
I have only one e-mail but I have a this problem.. so something doesn't go ...
How can I solve the problem?

Thanks
Best Regards
Alessandro

 

[Bitpalast]

Any hints in /var/log/maillog?

 

[bonny3]

Any hints in /var/log/maillog?

Thank you for reply,
This is some error in log:
May 25 11:30:33 occh postfix/smtp[9100]: 6A5DC301986: host mx-ha03.web.de[212.227.15.17] refused to talk to me: 554-web.de (mxweb010) Nemesis ESMTP Service not available 554-No SMTP service 554-Bad DNS PTR resource record. 554 For explanation visit Error messages | WEB.DE Postmaster
May 25 11:30:33 occh postfix/smtp[9101]: 9E0E2301845: host mx00.gmx.net[212.227.15.10] refused to talk to me: 554-gmx.net (mxgmx017) Nemesis ESMTP Service not available 554-No SMTP service 554-Bad DNS PTR resource record. 554 For explanation visit Error messages | GMX Postmaster
May 25 11:30:33 occh postfix/smtp[9103]: 76099300DC6: host mx-ha02.web.de[212.227.17.8] refused to talk to me: 554-web.de (mxweb113) Nemesis ESMTP Service not available 554-No SMTP service 554-Bad DNS PTR resource record. 554 For explanation visit Error messages | WEB.DE Postmaster
May 25 11:30:33 occh postfix/smtp[9102]: 8614E301ECE: host mx00.emig.gmx.net[212.227.15.9] refused to talk to me: 554-gmx.net (mxgmx016) Nemesis ESMTP Service not available 554-No SMTP service 554-Bad DNS PTR resource record. 554 For explanation visit Error messages | GMX Postmaster
May 25 11:30:33 occh postfix/smtp[9100]: 6A5DC301986: to=<[email protected]>, relay=mx-ha02.web.de[212.227.17.8]:25, delay=403660, delays=403660/0.01/0.08/0, dsn=4.0.0, status=deferred (host mx-ha02.web.de[212.227.17.8] refused to talk to me: 554-web.de (mxweb110) Nemesis ESMTP Service not available 554-No SMTP service 554-Bad DNS PTR resource record. 554 For explanation visit Error messages | WEB.DE Postmaster)
May 25 11:30:33 occh postfix/smtp[9103]: 76099300DC6: to=<[email protected]>, relay=mx-ha03.web.de[212.227.15.17]:25, delay=256403, delays=256403/0.02/0.07/0, dsn=4.0.0, status=deferred (host mx-ha03.web.de[212.227.15.17] refused to talk to me: 554-web.de (mxweb011) Nemesis ESMTP Service not available 554-No SMTP service 554-Bad DNS PTR resource record. 554 For explanation visit Error messages | WEB.DE Postmaster)
May 25 11:30:33 occh postfix/smtp[9102]: 8614E301ECE: to=<[email protected]>, relay=mx01.emig.gmx.net[212.227.17.5]:25, delay=239713, delays=239713/0.01/0.1/0, dsn=4.0.0, status=deferred (host mx01.emig.gmx.net[212.227.17.5] refused to talk to me: 554-gmx.net (mxgmx115) Nemesis ESMTP Service not available 554-No SMTP service 554-Bad DNS PTR resource record. 554 For explanation visit Error messages | GMX Postmaster)
May 25 11:30:33 occh postfix/smtp[9101]: 9E0E2301845: to=<[email protected]>, relay=mx01.gmx.net[212.227.17.4]:25, delay=50954, delays=50954/0.01/0.11/0, dsn=4.0.0, status=deferred (host mx01.gmx.net[212.227.17.4] refused to talk to me: 554-gmx.net (mxgmx114) Nemesis ESMTP Service not available 554-No SMTP service 554-Bad DNS PTR resource record. 554 For explanation visit Error messages | GMX Postmaster)

 

[Bitpalast]

Regarding the server, I suppose you are using the PX-121 SSD by Hetzner. The errors in the mail log indicate that the PTR record was not set in Hetzner's robot backend. Login to the robot, add the PTR record for IPv4 and two records for IPv6: ... ::1 and ... ::2.

However, this is only a sideline issue. It is not the cause for the high CPU load. It seems that someone is trying to send a lot of spam through your server. You need to check the SMTP settings and allow authenticated mails only (no open relay!). I further suggest to limit the number of outgoing mails to something reasonable like 100 per hour using Plesk's outgoing mail control.

 

[bonny3]

Regarding the server, I suppose you are using the PX-121 SSD by Hetzner. The errors in the mail log indicate that the PTR record was not set in Hetzner's robot backend. Login to the robot, add the PTR record for IPv4 and two records for IPv6: ... ::1 and ... ::2.

However, this is only a sideline issue. It is not the cause for the high CPU load. It seems that someone is trying to send a lot of spam through your server. You need to check the SMTP settings and allow authenticated mails only (no open relay!). I further suggest to limit the number of outgoing mails to something reasonable like 100 per hour using Plesk's outgoing mail control.

Do you talk about this?
http://imageshack.com/a/img924/7789/Yx0zPn.jpg
How can I set it up?
Thanks

 

[Bitpalast]

You enter the host name that the IP address shall resolve to. For more details, please ask Hetzner support.

 

[bonny3]

You enter the host name that the IP address shall resolve to. For more details, please ask Hetzner support.

They have indicated this guide,
But I do not understand ...
Do I have to set PTR records in my DNS provider?
DNS-Reverse-DNS/en – Hetzner DokuWiki
in this guide How to setup Reverse DNS and PTR records
Real example:
Standard DNS: www.itworld.com -> 23.23.212.126 Reverse DNS: 23.23.212.126 -> ec2-23-23-212-126.compute-1.amazonaws.com.
Is correct?
Where do I find the server name?

 

[Bitpalast]

This is not a Plesk issue, it is a misconfiguration of the Reverse DNS entry. You will need to ask Hetzner for assistance for using their robot page.

 

[bonny3]

Ok,
anyway I have encountered the problem of overcurrent cpu,
When I have two outlook imap locations in the same e-mail...
this is not normal....