In sme server sometimes i cannot send email over outlook using sme server 8.1 release
when i send message it reach slowely why
using putty i write the following command
tail -f /var/log/qmail/current
and in messages i notice that message show to me
deferral: Connected_to_127.0.0.1_but_greeting_failed./Remote_host_said:_451_Upstream_SMTP_server_not_available/
This Message error is repeated every times
email send slowly then stop
How to solve this problem
my settings is already fixed from 5 years but the problem
starting before 10 days and until now still slowly sending
and sometimes not work
Receiving email is OK working good
server status success connected to internet
can you tell me what problem

As shown here and here you seem to have recurring problems understanding (or testing) connectivity with remote MTAs. If the remote host throws an error saying the "SMTP server is not available" then you can test connectivity by doing a curl, wget, GET or telnet to that remote host mail server port to see if it is not available. Note that (unless you have b0rked your MTA configuration or are forced to work with a not-so-well behaving MTA) any mail for any unavailable remote host will be queued for re-send cycles as per mail RFCs. So start by testing connectivity.

Can you tell me what i do to trace the problem
how i use telnet
if possible help me

'telnet nameOfRemoteMailServer 25'.

name of my server is :mserver
and domain is altawi.com.sa
what i write actually telnet mserver.altawi.com.sa 25
or what
and when i write this
in putty of mail server
or from windows in any computer in network

any one can help me

Yes.


Any "plain" terminal window (cmd.exe, kterm, xterm, etc, etc) will do.
Start with your local workstation, then try again from the mail server itself.