Using 'mail' in a script to send mail on an alternate port?

tim914 · 01-16-2009, 09:48 AM

Hi Folks,

I'm working on a script to help Linux desktop users mange certain aspects of their desktop systems. Part of the script sends an email to a specified recipient on certain discoveries. This script works fine if the user's system is able to communicate with the mail server on port 25, but many users are now communicating with servers over alternate ports (the server listens for mail on a port other than 25 - Apple's mac.com server, for example).

Is it possible to tell the mail or mailx tool to use an alternate port? Or, is there another built-in command line mail tool that can send mail on an alternate port (the local system might not have the mail server process configured or running)?

Thanks,
Tim

trickykid · 01-16-2009, 10:06 AM

Well, all standard SMTP or MX records will use port 25 for mail delivery. It's not up to your mail client to pick the port of the mail server on the recieving end. When you use the mail or mailx command, it's using the local machine or server on port 25 to send the email out.

If you take a closer look at mac.com, it's just an alias for these MX records or hosts handling the mail which all listen on port 25 as I was able to telnet to each:

Code:

trickykid@myserver:~$ host mac.com
mac.com has address 17.250.248.32
mac.com mail is handled by 10 smtp-mx1.mac.com.
mac.com mail is handled by 10 smtp-mx2.mac.com.
mac.com mail is handled by 10 smtp-mx3.mac.com.
mac.com mail is handled by 10 smtp-mx4.mac.com.
mac.com mail is handled by 10 smtp-mx5.mac.com.
mac.com mail is handled by 10 smtp-mx6.mac.com.

tim914 · 01-16-2009, 10:36 AM

Quote:

Originally Posted by trickykid

If you take a closer look at mac.com, it's just an alias for these MX records or hosts handling the mail which all listen on port 25 as I was able to telnet to each

I never claimed that they didn't accept port 25 connections. However, many home users are connected via ISP's that block port 25 for all the right reasons. For these, Apple and others allow connection via port 587 (or 465 as a legacy alternate). This is where I'm coming from.

More relevant ideas?

Tim

trickykid · 01-16-2009, 02:35 PM

Quote:

Originally Posted by tim914

I never claimed that they didn't accept port 25 connections. However, many home users are connected via ISP's that block port 25 for all the right reasons. For these, Apple and others allow connection via port 587 (or 465 as a legacy alternate). This is where I'm coming from.

More relevant ideas?

Tim

Well yeah, for good reason to not allow users to have mail servers that are potential hosts to serve up spam.

Incoming is usually blocked but not outgoing. You should rewrite your rules so you're local box just sends the email through your ISP's SMTP provided server to send emails in this type of case.

tim914 · 01-16-2009, 03:23 PM

I don't want to sound ungrateful, but I don't think that you understand what I'm asking.

Regardless of right or wrong (I think it's right), many smart ISP's block port 25 outbound as well as inbound to prevent users' computers that have become members of botnets from sending mail directly. It's more than just preventing the running of server services in non-business grade accounts.

Ah well, I just wrote my own tool to handle it properly and will include it with the script.

Tim