No route to host (port 25)

*I don't know to which Message Board I should post this message. Maybe there's a need for general Sys Admin forum or something?*

My problem is with my mail server.
Cannot send email out (using pine or within Perl script), but I can receive email sent to my server.

The following is the error log.
Apr 26 12:12:18 birdsky postfix/smtp[13348]: connect to mx2.mail.yahoo.com[216.136.129.18]: No route to host (port 25)
Apr 26 12:12:21 birdsky postfix/smtp[13348]: connect to mta-v1.mail.yahoo.com[128.11.68.59]: No route to host (port 25)

Don't know if it's my setting problem or my ISP blocks the mail sent from user's server due to spamming issue.

Can anyone help?

Yahoo! does not permit relaying. In other words, you cannot connect to their SMTP server unless you have an IP within their domain. Many ISPs do this. You will need to use the SMTP server of the ISP that provides your access and only use the Yahoo! POP3 server.

Oh, and this is a forum for developers, not SAs. However, out of all the possible places, "beginners" would probably have been more appropriate. I'm not suggesting anything, but this just has absolutely nothing to do with perl.

Thanks.

But I am using my own SMTP mail server, not Yahoo's.

I use Mail::Sendmail and have the SMTP setting set to "localhost" (if I change it to the SMTP server provided by my ISP, ie. smtp.someisp.com, then it works fine)

The above "No Route to Host" message is generated by the mail server on localhost. It looks up the ip and recipient MTA address by itself.

Yes, this is my mail server's setting problem but not Perl's. Just wondering if anyone knows what goes wrong.

What happens when you try to mail yourself (not through localhost, but the fully qualified domain)? Also, do you have a static IP and a domain associated with said IP? Finally, who is your ISP? Road Runner, for instance, specifically blocks traffic to port 25.

I can receive emails from both outside hosts and localhost, but I don't have a static IP. I got a domain name from no-ip.com (birdsky.no-ip.com) and it works fine.

The problem is at sending (outgoing emails). My ISP is hknet.com, which is at Hong Kong (used to be Road Runner at USA, and they scanned the network to see who has relay open for other)

So I guess it's the ISP who blocks the outgoing emails orginated from my own mail server (doesn't allow us to be the spammers)...

I realize the problem is outgoing mail. You are missing the point. If you send to yourself, you are creating both an outgoing and incoming connection. How else do you think the mail is going to get to you?!

On an aside, hknet (at least in the past) has been a haven for spammers. It's interesting to note that this is changing?

Yes, it works if I send an email to myself thru with an FQDN.

I guess when it looks up the destination server, it found that is actually itself, right? Or something like that...

I am not really sure how this works... Just guessing.

When you use an FQDN, it leaves your machine and goes to your gateway (probably ISP's router). The router is the device that sends it back. I bet you they have blocked calls to port 25. Ask them. What could it hurt?

Thanks!

You're welcome.