ToolsSending Server IP Address

Sending Server IP Address


Most of the decisions that Road Runner's inbound mail servers make with regard to accepting a given message are keyed to the IP address of the server attempting to connect to Road Runner's inbound mail servers. With today's complex network layouts, it's not always obvious, even to the persons responsible for the server in question (and certainly almost never to the users of the server) which IP address is actually being used to connect to remote sites when a server sends mail; to help senders see what our servers see, we've got two tools available.

Automated Testing

The simplest test for anyone to use, and likely the only one available to a user of a mail server trying to send mail to Road Runner customers, is to send an email to the address that is not hosted on our customer mail platform.

Manual Testing (telnet to port 25)

If you're an administrator of a server that may be having issues getting mail to Road Runner customers, and you've got the ability to run a telnet command from the server in question, attempting to connect to port 25 on our inbound mail servers is another way for you to see what IP address we're seeing on our servers.

There are three sets of inbound servers for Road Runner customer mail, and while the policies and block lists in use are the same on all three sets, it may be useful to you to verify connectivity to each set of servers. Those sets of servers are:

  • cdptpa-pub-iedge-vip.email.rr.com and dnvrco-pub-iedge-vip.email.rr.com
  • mx1.biz.rr.com and mx2.biz.rr.com

For each of our inbound sets listed above, choose one hostname from each, and on the command line on your server, run the following command:

telnet $SERVER_NAME 25

For example:

telnet cdptpa-pub-iedge-vip.email.rr.com 25

Successful connection

Servers that are successful in connecting to our inbound servers will see, after a few seconds, a display that looks like this:

# telnet cdptpa-pub-iedge-vip.email.rr.com 25 Trying 107.14.166.70... Connected to cdptpa-pub-iedge-vip.email.rr.com. Escape character is '^]'. 220 Welcome to Road Runner. NO UCE *** FOR AUTHORIZED USE ONLY! ***

The key line in the above is the "220 Welcome to Road Runner...".

Once you've gotten to the 220 line, the next command for you to issue is either "EHLO your.domain.tld" or "HELO your.domain.tld":

EHLO example.com

HELO example.com

Our servers will accept either, and will respond with a series of lines that include the IP address of your server, like so:

250 2.0.0 cdptpa-iedge05 says EHLO to IP.ADD.RE.SS:39072
250-8BITMIME
250-ENHANCEDSTATUSCODES
250 PIPELINING

or

250 2.0.0 cdptpa-iedge05 says HELO to IP.ADD.RE.SS:39072

The actual IP address of the connecting server will be displayed where we've written 'IP.ADD.RE.SS". Once you've seen that, you can just issue a QUIT command.

Here's a full example session:

# telnet cdptpa-pub-iedge-vip.email.rr.com 25
107.14.166.70...
Connected to cdptpa-pub-iedge-vip.email.rr.com.
Escape character is '^]'.
220 Welcome to Road Runner. NO UCE *** FOR AUTHORIZED USE ONLY! ***
EHLO example.com
250 2.0.0 cdptpa-iedge05 says EHLO to 192.168.1.1:39072
250-8BITMIME
250-ENHANCEDSTATUSCODES
250 PIPELINING
QUIT
221 cdptpa-iedge05 closing connection
Connection closed by foreign host.

Failed Connection

If you're successful in reaching our servers but your IP is being blocked or otherwise rejected here, instead of getting the '220 Welcome to Road Runner...' greeting line, you'll something else, typically starting with either a 4 (e.g., 421) or a 5 (e.g., 550), and the error message will include your connecting IP, as in the following example:

# telnet cdptpa-pub-iedge-vip.email.rr.com 25
Trying 107.14.166.70...
Connected to cdptpa-pub-iedge-vip.email.rr.com.
Escape character is '^]'.
554 5.7.1 - ERROR: Mail refused - <172.28.1.1> - See URL OF BLOCKLIST GOES HERE
Connection closed by foreign host.