sendmail:NOQUEUE:Null connection - what does this mean?

[A.W.R]

Hi,

I have a few Alpha Servers running Tru64UNIX v5.1A. If I look in the syslog.dated mail.log file the following message occurs numerous times:-

sendmail:NOQUEUE:Null connection from [163.197.34.243]

If anyone has any ideas on what this message means, and whether I should be concerned about it?

Thanks
Andrew

[Steven Schweda]

A Google search for:
sendmail NOQUEUE
found:
http://www.sendmail.org/faq/section4
http://www.sendmail.org/faq/section4#4.18

[...]
18.What does "NOQUEUE: Null connection from ..." mean?
[...]

Could be informative. (This new Inter-Web
thing is a miracle.)

[Steven Schweda]

Also, I'd guess that any system in South
Africa with no reverse DNS data probably
isn't one with any valuable message for you,
but that's just my guess.

[Kapil Jha · Accepted solution]

I found this on net
-------
A "null connection" is when sendmail gets a connection to its TCP port, and
sends its banner, and the remote client either
A) closes the connection without doing anything or
B) issues only the QUIT command, which closes the sendmail connection immediately.

Try telnetting to your mailserver port 25, and then closing the telnet
without doing anything. You'll see it.

Chuck's SNMP monitoring system is probably checking to see that the SMTP
service is up and running by connecting to its TCP port
-----
Plus u can check if port on mail server is working or not,is this problem with only ne server or other servers are afected.


BR,
Kapil