Expose-node-metrics.cattle-prometheus scanning constantly port 25

HI,

I have a container with port 25.

Port Name	Publish the container port	Protocol As a		    On listening port	 
http	    25	 	                    TCP	 	 ClusterIP	 	Same as container port

The Service is exposed via a NodePort

Port Name    Publish the service port		Protocol		Target Port		Node Port	 
http	 	     25	 	                                TCP	 	         25	 	        30840

and the container is full of logs like this:

Jul 09 11:12:35 mailhost postfix/smtpd[1052]: disconnect from unknown[10.0.0.1] ehlo=1 quit=1 commands=2
Jul 09 11:12:37 mailhost postfix/smtpd[1052]: connect from 10.0.2.1.expose-kubelets-metrics.cattle-prometheus.svc.cluster.local[10.0.2.1]
Jul 09 11:12:37 mailhost postfix/smtpd[1052]: lost connection after CONNECT from 10.0.2.1.expose-kubelets-metrics.cattle-prometheus.svc.cluster.local[10.0.2.1]
Jul 09 11:12:37 mailhost postfix/smtpd[1052]: disconnect from 10.0.2.1.expose-kubelets-metrics.cattle-prometheus.svc.cluster.local[10.0.2.1] commands=0/0
Jul 09 11:12:39 mailhost postfix/smtpd[1052]: connect from 10.0.2.1.expose-kubelets-metrics.cattle-prometheus.svc.cluster.local[10.0.2.1]
Jul 09 11:12:39 mailhost postfix/smtpd[1052]: lost connection after CONNECT from 10.0.2.1.expose-kubelets-metrics.cattle-prometheus.svc.cluster.local[10.0.2.1]
Jul 09 11:12:39 mailhost postfix/smtpd[1052]: disconnect from 10.0.2.1.expose-kubelets-metrics.cattle-prometheus.svc.cluster.local[10.0.2.1] commands=0/0
Jul 09 11:12:40 mailhost postfix/smtpd[1052]: connect from 10.0.2.1.expose-node-metrics.cattle-prometheus.svc.cluster.local[10.0.2.1]
Jul 09 11:12:40 mailhost postfix/smtpd[1052]: disconnect from 10.0.2.1.expose-node-metrics.cattle-prometheus.svc.cluster.local[10.0.2.1] ehlo=1 quit=1 commands=2

Anyone got any idea what is going on here ?
Thanks for any advise.