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 BlockingMany 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:
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.