pls. help i used sendmail to send email, i open my mailog and it says no route to host, i don't knoe what exactly the problem

That's not much to go on! Either post your log or detail in full all errors recorded in the log.

nothing to do with programming. moved to Linux - Newbie.

this is my log


Apr 23 00:42:34 my sendmail[24276]: l3MGbdc9024274: to=<jez_pag@yahoo.com>, ctladdr=<root@my.com> (0/0), delay=00:04:30, xdelay=00:04:09, mailer=esmtp, pri=120397, relay=a.mx.mail.yahoo.com. [209.191.118.103], dsn=4.0.0, stat=Deferred: a.mx.mail.yahoo.com.: No route to host

i can't send an email but i can receive.

this is my log when i receive mail from yahoo.com

Apr 23 00:49:47 my sendmail[24366]: l3MGnPcK024365: to=root, delay=00:00:01, xdelay=00:00:00, mailer=local, pri=32106, dsn=2.0.0, stat=Sent

Apr 23 00:49:47 my sendmail[24365]: l3MGnPcK024365: from=<jez_pag@yahoo.com>, size=1872, class=0, nrcpts=1, msgid=<580049.15600.qm@web58706.mail.re1.yahoo.com>, proto=SMTP, daemon=MTA, relay=web58706.mail.re1.yahoo.com [66.196.100.183]

you really should read this:
http://www.linuxquestions.org/questi...d.php?t=228382

do you have the MX records set up ok?
do u use smart host?
if not, you should consider using it

yes i have MX records set up ok,

nslookup -q=mx my.com
Server: 202.78.97.41
Address: 202.78.97.41#53

Non-authoritative answer:
my.com mail exchanger = 5 mail.my.com.

Authoritative answers can be found from:
my.com nameserver = ns5.no-ip.com.
my.com nameserver = ns3.no-ip.com.
my.com nameserver = ns2.no-ip.com.
my.com nameserver = ns1.no-ip.com.
my.com nameserver = ns4.no-ip.com.
mail.my.com internet address = 210.4.3.71
ns3.no-ip.com internet address = 63.208.74.226
ns4.no-ip.com internet address = 198.65.102.15
ns5.no-ip.com internet address = 212.100.249.200
ns1.no-ip.com internet address = 216.66.37.13
ns2.no-ip.com internet address = 204.16.252.6

>my smart host
define(`SMART_HOST',`mail.my.com')

Forcing the attempted delivery of 1 selected messages ..
Running /var/spool/mqueue/l3NIn8m4028522 (sequence 1 of 1)
<jez_pag@yahoo.com>... Connecting to f.mx.mail.yahoo.com. via esmtp...
<jez_pag@yahoo.com>... Connecting to d.mx.mail.yahoo.com. via esmtp...
<jez_pag@yahoo.com>... Connecting to g.mx.mail.yahoo.com. via esmtp...
<jez_pag@yahoo.com>... Connecting to c.mx.mail.yahoo.com. via esmtp...
<jez_pag@yahoo.com>... Connecting to b.mx.mail.yahoo.com. via esmtp...
<jez_pag@yahoo.com>... Connecting to a.mx.mail.yahoo.com. via esmtp...
<jez_pag@yahoo.com>... Connecting to e.mx.mail.yahoo.com. via esmtp...
<jez_pag@yahoo.com>... Deferred: e.mx.mail.yahoo.com.: No route to host

telnet yahoo.com 25
Trying 216.109.112.135...
telnet: connect to address 216.109.112.135: No route to host
Trying 66.94.234.13...
telnet: connect to address 66.94.234.13: No route to host
telnet: Unable to connect to remote host: No route to host

check in your mail server whether the firewall is runing and is it letting to make connections on port 25 through it. If the firewall in the server isn't configured to accept connections which are coming to port 25 you are getting the message "no route to host" on the client machine which runs the MUA.

mail.my.com domain points to your machine external IP?
if this is an induvidual server, as far as i know, "big" mail servers drop connection from unknown addresses
so then u use smart host to define your ISPs mail server and send mail through your ISPs mail server

if i try to telnet to yahoo.com 25 remote host drops the connections in an instance
and if i change my smart host or comment it out i can't send mail to some recipients either
as the "main" mail server think i'm a spammer