What to do if your email is being rejected by LOCL.net email servers.

Is your email is being rejected by our servers with a message like this:

 554 5.7.1 <yourhost.yourdomain.com[10.10.10.1]>: Client host rejected: please_use_SMTP_relay_of_your_isp,_or_setup_non-generic_dns.

If so, here's the story:

In an effort to curb abuse of our email servers and limit the amount of spam inflicted upon our users, LOCL.net does not accept email from computers with dynamically assigned IP addresses, or hosts that have generic DNS setup.

If you get the above message, here's what to do:

The easiest solution is to use the mail server of your ISP to send relay email, as they almost certainly have their DNS setup properly in the way we would like. If you're not sure how to setup your mail client to do this, please contact your ISP.

If you have a static IP address and want to be able to send email through your own mail server, you will need to contact your ISP and have them setup non-generic DNS for your IP address.

If these suggestions don't work, some people find it easiest to use one of the many free web based email systems.

What is generic DNS?

When you make a connection to our servers, we use your IP address to perform a reverse lookup to find the name listed for your computer in the domain name service.  We consider you to have generic DNS if the hostname returned contains:

  • An IP address
  • The words pool, dhcp, dynamic
  • The words dsl, ppp, pub
  • The words server or host
  • The words dial or dialup
  • The words cable or modem
  • Any indication that the host is a nameserver, ie: ns1, ns2 etc. (a large influx of spam from apparently compromised nameservers has necessitated this temporary policy)
  • Any other indicators that the hostname is not specific to you or your organization

How do I check for generic DNS?

While the specifics differ by operating system, the basic procedure is the same:

  • retreive your machine's IP address
  • perform a DNS query to look up the PTR record for that IP address

Note that you have to specify your IP address for purposes of this query in reverse.  For example, if your IP address is A.B.C.D, you need to look up D.C.B.A.in-addr.arpa. instead.

Here are some examples using the IP address 208.82.236.208:

Windows

Open a command prompt and type the following:

C:\Documents and Settings\username>nslookup
Default Server:  my.nameserver.org      <-------- will be different on your machine, don't panic!
Address:  192.168.168.1                      <-------- same here
> set query=ptr
> 208.236.82.208.in-addr.arpa.
208.236.82.208.in-addr.arpa     PTR     www.craigslist.org
>

You can see the result of the lookup after the letters PTR above.

Linux, MacOS, other UNIX

Open Terminal.app and type the following into the shell:

$ dig +short 208.236.82.208.in-addr.arpa. ptr
www.craigslist.org.
$

The results of the lookup are shown immediately after the command.

Still Broken?

If you have a static IP address, run a mail server and do not have generic DNS, and are continuing to run into trouble, please send email to support@locl.net. Be sure to include the complete headers, rejection message, and output of your DNS lookup (as shown in the above examples) so that we're able to determine exactly what is happening.