Resolved Ports for mail server?

[CoyoteKG]

Hello,

I'm a little bit confused.
Plesk firewall is disabled.
Only I'm using for now is Hetzner's firewall.
I already opened ports 143,993,587


And I'm able to send mails with 587 port, but can't receive it.
When I disable hetzner's firewall, I instantly receiving mails (but not that ones I sent while firewall was up).

Where I'm in wrong about ports?
When hetzner's firewall is up, I can telnet on ports 143, 993 and 587. Which port I also need to open.
Is it important to have also port 25 for incoming mails?!

 

[UFHH01]

Hi CoyoteKG,

Is it important to have also port 25 for incoming mails?!

Yes.

Pls. check: => Which Ports Need To Be Opened for all Plesk Services to Work with a Firewall?

 

[mr-wolf]

Is it important to have also port 25 for incoming mails?!

I sincerely don't understand why anyone without that basic knowledge would have a need for Plesk.
I am thinking of reasons, but I can't come up with any.

It may sound offending, but i really don't mean it that way, I'm curious to find out why you're using Plesk and what you want to do with it.

 

[CoyoteKG]

I will like your post, you are totally right and you are deserve it with your very usable post.

I know what is port 25, because that I was wondered why I need it to be open if I'm using 587.
I belive that is basic thing so please maybe you can spend your valuable time and help me to understand that basic thing. That would be better then your previous post

But yes, just to say, I open port 25, and pop3 ports and now it working.

 

[mr-wolf]

In 1982 it was decided to use port 25 for the Simple Mail Transfer Protocol
Simple Mail Transfer Protocol - Wikipedia

Port 587 is used for mail clients although port 25 can be used for that as well.

I can give much more information about this subject but that can get complicated. That's what happens with things that start out as Simple Mail Transfer Protocol

 

[CoyoteKG]

OK, so from that link

... client mail applications typically use SMTP only for sending messages to a mail server for relaying. For retrieving messages, client applications usually use either IMAP or POP3.

OK, still not understand... I understand that SMTP port is using for sending mail, and I have not problem with that, I had problem with receiving mails, so my conclusion was that on server where I receiving the message I need to have incoming ports open, not outgoing.

And my thinking is wrong?
Obviously yes, because now I can receive mails on that server...

 

[WebHostingAce]

@CoyoteKG

Open POP3 and IMAP Ports(Both Secure and unsecure) to receive mails.

Also leave Port 25 open inbound, server to talk to other servers.

 

[mr-wolf]

You should really need to work on your logic.

You are not the one to decide to use another port than 25 for SMTP.
The whole world is using port 25 for SMTP. I don't think you are able to convince each one of them to use another port than 25. Until then you really need open port 25 so you can receive mail from others as that is the only port on which they will send mail to you.

You chose to NOT read the important part of the page I referred you to (the part you replaced with dots) and focused on the part of the sentence that's less relevant. Then it starts with a new sentence which again applies to your problem.

If your server is connecting to other server's port 25 to send mail, then it's obvious that other servers would like to reach your server on port 25 so they can send mail to you.

When your server is using port 25 to send mail, they mean they use the OTHER server's port 25. The port it's using on your server is random and also irrelevant.

Your firewall is most probably not blocking any outgoing traffic, so you don't even need to worry about outgoing mail.

So, you did nothing to get outgoing smtp working.

Still...
I don't know why you bought Plesk if you don't already know all this.
And why did you replace the Plesk firewall manager (it's not the firewall itself) for some other thing if you don't know how a firewall works?

Plesk is made for engineers that like to have a web based manager to do stuff they could do without it, but is too much work to manage.

 

[mr-wolf]

@CoyoteKG

Open POP3 and IMAP Ports(Both Secure and unsecure) to receive mails.

Also leave Port 25 open inbound, server to talk to other servers.

Your server is not receiving mail through pop or imap. It ONLY receives mail through SMTP and this is on port 25.

The other ports (110, 143, 465, 587, 993 & 995) are there to communicate with your mail client.

 

[mr-wolf]

@CoyoteKG

I now think I know why you have such a hard time understanding it.
You seem to think that traffic is using the same port on both sides.
Typical TCP/IP traffic works like this.
We've agreed that each service has their own port.
For http it's port 80, for https it's 443, smtp it's 25 and much more.
When an initiator wants to "talk" smtp he opens a random free TCP socket on its computer that has an IP and a port (often a high one) and contacts the other side's IP and port 25. With that packet the source IP and source port is sent.
When the server answers it sends its reply to that IP and port. The initiator knows it's the answer as the answer-packet contains that same IP and port 25.

So when they write "SMTP uses port 25" they mean the destination port.

When we speak of receiving mail then the destination will be your server, so it's port 25 of your machine.
When we speak is sending mail, it's someone else's server on port 25.

So, it's always port 25. The destination port is what counts.

Most firewalls are configured to block all the ports for incoming traffic. Outgoing it doesn't block.
If you send mail to the IP 30.20.30.20 (port 25) from port 45342 then the firewall will remember that port and IP and it will accept incoming traffic from IP 30.20.30.20:25 coming in on port 45342.
It will not accept packets from another IP on that port. It will not even accept packets from that IP coming from another port. Only traffic from port 25 of 30.20.30.20 is accepted on port 45342.
Nothing extra needs to be configured for that.

When you want to receive mail, you need to open port 25 for the world. If you don't, that traffic on port 25 will be dropped as the firewall is instructed to block all ports. Your smtp server will not be reached.

I hope I've helped you now understanding it better.

 

[CoyoteKG]

This post is very useful, unlike previous where you indirectly humiliate me...
I'm very thankful for your last post.

 

[mr-wolf]

This post is very useful, unlike previous where you indirectly humiliate me...
I'm very thankful for your last post.

I wouldn't say humiliate, but it could have been friendlier. Do know I really wanted to help you from the start.