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ISP Mail Server

Offline eiceic

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ISP Mail Server
« on: May 25, 2006, 03:30:24 AM »
The SME server re-routes all port 25 traffic to it's SMTP server.  I'm trying to use my ISP's SMTP server and I filled in this prompt on the e-mail tab of server-manager

Address of Internet provider's mail server  mail.mt.net


After applying the change, I still see my linux server is still interecepting the traffic:

I type:

   Telnet mail.mt.net 25

I get
   220 linux2.georgesdistributing.com mailfront ESMTP


Is that correct?  Does the linux SMTP talk to the mail client and then pass it off to the ISP mail server?  

Thanks,

Chris Buechler

Offline cactus

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Re: ISP Mail Server
« Reply #1 on: May 25, 2006, 09:57:50 AM »
Quote from: "eiceic"
The SME server re-routes all port 25 traffic to it's SMTP server.  I'm trying to use my ISP's SMTP server and I filled in this prompt on the e-mail tab of server-manager

Address of Internet provider's mail server  mail.mt.net


After applying the change, I still see my linux server is still interecepting the traffic:

I type:

   Telnet mail.mt.net 25

I get
   220 linux2.georgesdistributing.com mailfront ESMTP


Is that correct?  Does the linux SMTP talk to the mail client and then pass it off to the ISP mail server?  

Thanks,

Chris Buechler
Are your trying this from your internal network? If your provider blocks port 25 this will not work from outside your network. You need to modify your DNS recordss to have the mail-server of your ISP te be configured as a backup or mail-relay server:

Port 25 Blocking

Many ISPs are blocking what is called "Port 25" which is the port used to send e-mail. They are doing this to cut down on the amount of spam that is sent from their networks.

All e-mail sent via the Internet is routed through the port 25, the channel used for communication between an e-mail client and an e-mail server. Even though port 25 blocking will probably become an industry standard, however, the filter can create problems for e-mail servers and block legitimate e-mail as well as spam.

Port 25 blocking allows ISPs to block spam sent out through their networks, but it tends to punish the innocent that have a need to send through e-mail servers other than those belonging to their ISP. The ISPs that block port 25 require their SMTP server to be used instead of the remote SMTP server or a SMTP server running on your computer.

All e-mail sent via the Internet is routed through port 25. When an e-mail server that runs on your computer delivers messages, it always uses port 25 to transmit data to remote e-mail servers. Therefore, if your ISP is blocking the port, your messages will not get through.

The DNS entries should look something like this:
Code: [Select]
MX 10 your.mail.server.at.your.domain.
MX 20 your.providers.mail.server

All external mail servers will try to drop the mail at your server but your provider does not allow for this, so the mailservers lookup the next mailserver which is the one of your provider. They will deliver the mail there. The mailserver of your provider normally can see your mailserver and is able to deliver the mail to your mailserver. This is called mail-relay.
Be careful whose advice you buy, but be patient with those who supply it. Advice is a form of nostalgia, dispensing it is a way of fishing the past from the disposal, wiping it off, painting over the ugly parts and recycling it for more than its worth ~ Baz Luhrmann - Everybody's Free (To Wear Sunscreen)

Offline eiceic

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ISP SMTP
« Reply #2 on: May 25, 2006, 11:38:33 AM »
Hi,

The ISP is not blocking port 25 -  I just want to use their SMTP because I am occasionally getting messages like this..

Connected to 69.17.117.60 but greeting failed.
Remote host said: 554 mail20.sea5.speakeasy.net You Must have reverse DNS
setup in order to relay mail. Please set http://www.speakeasy.net/rdns
I'm not going to try again; this message has been in the queue too long.

--- Below this line is a copy of the message.


It seemed easier to just use their SMTP instead of getting them to set up a reverse DNS entry on the static IP.

Thanks,

Chris Buechler

Offline cactus

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Re: ISP SMTP
« Reply #3 on: May 25, 2006, 11:45:42 AM »
Quote from: "eiceic"
Hi,

The ISP is not blocking port 25 -  I just want to use their SMTP because I am occasionally getting messages like this..

Connected to 69.17.117.60 but greeting failed.
Remote host said: 554 mail20.sea5.speakeasy.net You Must have reverse DNS
setup in order to relay mail. Please set http://www.speakeasy.net/rdns
I'm not going to try again; this message has been in the queue too long.

--- Below this line is a copy of the message.


It seemed easier to just use their SMTP instead of getting them to set up a reverse DNS entry on the static IP.

Thanks,

Chris Buechler
Still I think you need to setup a DNS entry as all mail is delivered at port 25 by default, as your mailserver accepts connections at port 25 this will be the first server to accept the mail, your providers mail server will not even be tried I guess as the mail reached its destination.

You can not force other mail servers to first try at your address and afterwards at your providers server other than with DNS. You will probably have to configure your providers mail server in the DNS to be the first (and maybe only) mail server.
Be careful whose advice you buy, but be patient with those who supply it. Advice is a form of nostalgia, dispensing it is a way of fishing the past from the disposal, wiping it off, painting over the ugly parts and recycling it for more than its worth ~ Baz Luhrmann - Everybody's Free (To Wear Sunscreen)

Offline CharlieBrady

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Re: ISP Mail Server
« Reply #4 on: May 25, 2006, 04:20:47 PM »
Quote from: "eiceic"

Is that correct?  Does the linux SMTP talk to the mail client and then pass it off to the ISP mail server?  


Yes and Yes.

Offline CharlieBrady

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Re: ISP SMTP
« Reply #5 on: May 25, 2006, 04:22:28 PM »
Quote from: "cactus"

Still I think you need to setup a DNS entry as all mail is delivered at port 25 by default, as your mailserver accepts connections at port 25 this will be the first server to accept the mail, your providers mail server will not even be tried I guess as the mail reached its destination.


Chris is talking about outbound SMTP and you are raising issues only relevant to inbound SMTP.

Offline cactus

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Re: ISP SMTP
« Reply #6 on: May 25, 2006, 07:29:37 PM »
Quote from: "CharlieBrady"
Chris is talking about outbound SMTP and you are raising issues only relevant to inbound SMTP.
Ooops, my mistake.  :oops:
Be careful whose advice you buy, but be patient with those who supply it. Advice is a form of nostalgia, dispensing it is a way of fishing the past from the disposal, wiping it off, painting over the ugly parts and recycling it for more than its worth ~ Baz Luhrmann - Everybody's Free (To Wear Sunscreen)