centos 7, sendmail error: dsn=4.0.0, stat=Deferred: Connection timed out

sarahlin · 07-04-2016, 05:58 AM

Hi there,

i have install sendmail on my centos 7, on a server with subdomain.domain.com, I can receive mail send from the sever to user1@subdomain.domain.com, and user2@domain.com; but when i try to send mail outside the domain.com, it failed with "dsn=4.0.0, stat=Deferred: Connection timed out" error;

Anyone have any ideas what i miss on the server/sendmail configuration?

thanks.

TenTenths · 07-04-2016, 07:10 AM

DNS?
Outbound firewall?
Being blocked at the receiver end?

sarahlin · 07-05-2016, 07:31 AM

Quote:

Originally Posted by TenTenths

DNS?
Outbound firewall?
Being blocked at the receiver end?

new to admin job, wondering if anyone can tell me more detail about the steps i should run to check, and what's the expected outcome from the check;

the server is an external facing box, www running on it, so i am kind of afraid to mess around the box.

thank you in advance.

ardvark71 · 07-05-2016, 08:24 AM

Quote:

Originally Posted by sarahlin

new to admin job, wondering if anyone can tell me more detail about the steps i should run to check, and what's the expected outcome from the check;

the server is an external facing box, www running on it, so i am kind of afraid to mess around the box.

Hello and welcome to the forum

By "admin job," do you mean system administrator? If so, not to try and sound rude in any way but you may be way in over your head from what you described. The things that TenTenths described are not only common aspects to the job but involve software and typically do not require you to do anything to the hardware.

On the firewall side of things, here are some pages that might be of help...

https://www.linode.com/docs/security...alld-on-centos

http://www.liquidweb.com/kb/how-to-s...d-on-centos-7/

http://www.liquidweb.com/kb/how-to-s...d-on-centos-7/

http://www.codero.com/knowledge-base/questions/377/

http://www.tecmint.com/firewalld-rules-for-centos-7/

Also, you should be able to open a terminal and find out the what the rules are for your firewall by using these commands, as mentioned in the first link above...

Code:

firewall-cmd --direct --get-all-chains

Code:

firewall-cmd --direct --get-all-rules

Regards...

sarahlin · 07-05-2016, 11:53 AM

Quote:

Originally Posted by ardvark71

Hello and welcome to the forum

By "admin job," do you mean system administrator? If so, not to try and sound rude in any way but you may be way in over your head from what you described. The things that TenTenths described are not only common aspects to the job but involve software and typically do not require you to do anything to the hardware.

On the firewall side of things, here are some pages that might be of help...

https://www.linode.com/docs/security...alld-on-centos

http://www.liquidweb.com/kb/how-to-s...d-on-centos-7/

http://www.liquidweb.com/kb/how-to-s...d-on-centos-7/

http://www.codero.com/knowledge-base/questions/377/

http://www.tecmint.com/firewalld-rules-for-centos-7/

Also, you should be able to open a terminal and find out the what the rules are for your firewall by using these commands, as mentioned in the first link above...

Code:

firewall-cmd --direct --get-all-chains

Code:

firewall-cmd --direct --get-all-rules

Regards...

thank you for the links, i will check them out..

per "Admin job", which is not my main job, just it happen the sendmail doesn't work on the box, i have to find out how to get it work.. i am a software developer.

there are just too many things to understand, and learn!

ardvark71 · 07-05-2016, 12:36 PM

Quote:

Originally Posted by sarahlin

i am a software developer.

Ah, that makes more sense now.

Regards...