Edit :
first thing you have to know is "no outgoing server configured" not a specific error description because that error or warning appears in a lot of cases even you have a working outgoing mail server working fine like this case.
After spending days and weeks trying to solving this issue finally i found the solution is to reduce th MTU (maximum transfere unit) for ubuntu server in interfface file in this location :
etc/network/interface and add mtu line like this :
# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).
# The loopback network interface
auto lo
iface lo inet loopback
# The primary network interface
auto eth0
iface eth0 inet static
address 192.168.100.230
netmask 255.255.255.0
network 192.168.100.0
broadcast 192.168.100.255
gateway 192.168.100.1
# dns-* options are implemented by the resolvconf package, if installed
dns-nameservers 8.8.8.8 192.168.100.5
dns-search exd.local
mtu 1492
this issue happened when my company change the network router and it is a network issue but you can fix that issu by set mtu to 1492.