View All Products
Compute
Storage
Databases
Networking
Developer Tools
Delivery
Security
Services
Industries
Pricing
Community
Engage With Us
Community ▶ Questions ▶ SMTP works only inside the box
Log in to Ask a Question

SMTP works only inside the box

email

Hello, everyone!

I just set up a sendmail in my CentOS 5.3 linux box.

And I am having problem accessing SMTP from the outside network.

When I try to telnet to SMTP inside linux console, it's okay.

Basically I used the same command in the Linux console and Windows Command Prompt.

telnet mail.example.com 25

I can ping to the mail.example.com so it's not DNS or ip problem.

I used iptables command to see if I set up firewalls but i didn't.

iptables -L

Any clues?

5 Replies

I'd run….

service iptables stop

just to make sure.

Can you connect to other port 25s? Many (most?) ISPs block outgoing traffic to port 25 to cut down on outgoing spam from hijacked computers.

Try:

telnet mail.hoopycat.com 25

I know that one's up and reachable. :-)

hoopycat

You are right!!

I tried your code and it didn't work. I guess I need to use ISP's SMTP.

There are some other options. You could use an SSH tunnel. Or you could use the submission port (587 I believe).

@Xan:

There are some other options. You could use an SSH tunnel. Or you could use the submission port (587 I believe).
Yeah, I've used 587 ever since Verizon started blocking 25.

Reply

Please enter an answer
Tips:

You can mention users to notify them: @username

You can use Markdown to format your question. For more examples see the Markdown Cheatsheet.

> I’m a blockquote.

I’m a blockquote.

[I'm a link] (https://www.google.com)

I'm a link

**I am bold** I am bold

*I am italicized* I am italicized

Log in to Reply
Community Code of Conduct