Sendmail - No route to host

[matto123]

On AIX 4.3 setting aspmx.l.google.com as the relay host gives "No route to host". I can ping the host and telnet to that address on port 25, but I cannot telnet to the hostname on port 25.

# ping -c 1 aspmx.l.google.com
PING aspmx.l.google.com: (209.85.225.27): 56 data bytes
64 bytes from 209.85.225.27: icmp_seq=0 ttl=49 time=77 ms
----aspmx.l.google.com PING Statistics----
1 packets transmitted, 1 packets received, 0% packet loss
round-trip min/avg/max = 77/77/77 ms

# telnet 209.85.225.27 25
Trying...
Connected to 209.85.225.27.
Escape character is '^]'.
220 mx.google.com ESMTP v4si3279980icx.53

# telnet aspmx.l.google.com 25
Trying...
telnet: connect: A route to the remote host is not available.
​

I tried to connect to another mailer (telnet mta1171.mail.mud.yahoo.com 25) and that connected.

# telnet mta1171.mail.mud.yahoo.com 25
Trying...
Connected to mta1171.mail.mud.yahoo.com.
Escape character is '^]'.
220 mta1171.mail.mud.yahoo.com ESMTP YSmtp service ready
​

So, we know that the hostname will resolve and that port 25 is not being blocked.
What do I look at next?

Thanks
-MattO

 

[iggsterman]

Since aspmx.l.google.com does not block incoming SMTP connections (I checked), please see if a local firewall is blocking outbound traffic to dst port 25.

 

[matto123]

The ping command shows that name resolution is working:

# ping -c 1 aspmx.l.google.com
PING aspmx.l.google.com: (209.85.225.27): 56 data bytes​

The telnet command shows that connections to that host on port 25 are allowed (no firewall blocking):

# telnet 209.85.225.27 25
Trying...
Connected to 209.85.225.27.​

This telnet command shows that I can connect using a hostname:

# telnet mta1171.mail.mud.yahoo.com 25
Trying...
Connected to mta1171.mail.mud.yahoo.com.​

So why does telnet aspmx.l.google.com 25 fail on the AIX machine?
- It works from every other machine on my network that I have tried.

 

[iggsterman]

Something is not healthy with their DNS. The address keeps changing - today it is 74.125.127.26. This host refuses connections on port 25. I would suggest using a different relay.