We have a web server (on Slicehost) with an IP address that has been blacklisted in at least one DNSRBL (FIVETEN).

The host is not currently a source of mail, in fact all mail for the domain goes through Google apps. The only association between the domain and the host is the "A" record. My understanding of blacklisting is that it's only servers in the SMTP path that matter.

Meanwhile mail (personal, direct email, not bulk) from the domain seems to be getting blocked and/or silently discarded by certain recipients. We may even have a case of a host refusing to send mail to the domain, which is also troubling (I haven't yet confirmed if this has happened more than once though).

The questions then:

  • can the lost email and the RBL'ed web server be a related phenomena?

  • if not what other troubleshooting do you recommend for the email issue?

Also I'd appreciate any comments on the relative importance of the FIVETEN DNSRBL, is it worth caring about? http://www.five-ten-sg.com/blackhole.php

  • I hope my recommendation of multirbl.valli.org or a comparable tool to investigate the actual scope of the issue will not in itself be considered spam or offtopic. Also makes for an excellent one-line-one-link answer to "why does xyz have problems sending us email?"... Dec 14, 2012 at 0:51

4 Answers 4


The entry in the Blacklist will be for the IP of the server, not the domain. Any domain sending email from that server would experience problems in doing so. There should be no link between your IP being blacklisted and your domain.

This is assuming you were not the cause of the IP getting blacklisted. If you were sending out Spam from your domain, it maybe that your domain has been blacklisted as well.

If that is not the case then its likely that the two issues are unrelated. There could be more general issues with your mail. Do you have proper Reverse DNS setup? A number of big mail providers look at these when deciding to deliver mail. Are you getting any bounce backs for undelivered mail. I'd say look at your mailserver logs, but obviously that's not possible with Gmail. If your paying for Apps for Domains, i'd take the issue up with Google.

  • Thanks-- it's a recently acquired server, any history of spam from that IP is unrelated to us or the domain in question.
    – user8379
    Nov 13, 2009 at 15:55


I know you've accepted an answer, but I wanted to ask you to please get in touch with SH support and tell them about the IP issue, and ask to either speak to or have it forward to the AUP team.

I work for Rackspace, the parent company of Slicehost, and we want to guard our IPs and those of our customers from improper blacklisting.


Some spam scoring looks at the IP addresses from Received: headers, not just the IP address that a mail was received from, and you can be seen as more likely to be spammy based on those Received: headers. So this can affect you, a little.

But fiveten itself? Ii's in the list of RBLs I poll to check that my own IPs aren't listed, but I don't know of anyone actively using it, because it's too inaccurate.

Use a search engine, plug in the name Al Iverson and a term like DNSBL. Al has done some comparative scoring of various DNSBLs and his pages will provide details of what's right or wrong with the RBL.


Currently, this should not affect a web server. However, changes in practice do happen and perhaps some day, someone will write a browser (or plug-in) that checks with DNSBLs. Therefore, I would suggest taking steps (if possible) to get your ip address de-listed from the DNSBL anyway.

Also, a listing on one DNSBL could be an indicator that you should check for listings elsewhere.

Multi-RBL checkers I use:

http://multirbl.valli.org/lookup/ (IPv6, IPv4, or domain name) http://www.blacklistalert.org/?q= (IPv4 or domain name) http://www.dnsbl.info/dnsbl-database-check.php?IP=_ (IPv4 only)

replace the underscore with your IP address.

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