Chances are you are on this page because an email you sent to one of the accounts handled by HSI was rejected. Due to the large amount of spam received by us and our customers, we have finally (and with considerable regret) implemented a policy of rejecting email coming from certain classes of IP addresses. Our goal is to reduce the amount of obvious spam while rejecting as little as possible proper email. As a result, we have adopted a fairly conservative approach to blocking email. The chances are pretty good that if we blocked your mail the system it is coming from has a problem. At the moment, we are basing our rejection of incoming email on the IP address of the sending system. There are three lists we use to determine IP addresses from which we will not accept email. The first is our internal list of addresses from which we have gotten repeated spam messages. Because we manage this list ourselves quite carefully, there is almost no chance that an email coming from one of these addresses is legitimate. An entry in this list has an associated txt record (which will show in the bounce message) that looks like "HSI spam Sept 2007". We are also currently using the spamhaus list. Our experience with other "block lists" has not been good, but this one seems to be pretty reliable so far. We are also blocking mail that comes from IP addresses we can identify as dynamic. These addresses are those used to temporarily route traffic to (typically home) users on networks like cable or dial-up access. Users on these networks should be sending email via the mail server assigned to them by their provider, not directly from their machines. Addresses that were blocked for this reason will have a comment in the rejection that uses the term "dynablock". If your email was rejected by our server, here are the steps we recommend: If you don't operate the mail server used to send the message, please pass the rejection message and a reference to this page along to whoever does If you do operate the server, check your IP address at the spamhaus web site. If it is listed, it is likely you have a real problem with your server and you should consider checking it out as the appropriate site suggests. If your IP address is dynamic, we suggest you switch to using the proper outgoing (SMTP) server for your provider. If you have exhausted reasonable attempts with spamhaus and for some reason cannot get yourself unlisted, send an email (or a fax if you can't find some other way to send an email) to us explaining the situation and what you have tried to do about it. If we believe the situation warrants it, we will "whitelist" your server, at least until we can investigate further. If your server is listed in our database send us your information and we'll investigate the situation. Please include full contact information and explain why you believe our listing is in error. Our servers have been unfairly and purposely included in the SPEWS database, so we know what it is like to be listed incorrectly. We also are really tired of getting tons of spam. We believe the approach we are using is reasonably fair and balanced, but are always ready to listen to other views and suggestions. If you wish to discuss the email blocking situation with us, we require only that you provide full contact information; if you don't we will simply throw away your message. By the way, we do our best not to allow messages from "services" like Spamarrest to get through to us. Most of these systems are so badly written and/or configured that most of the "verification" messages we receive have nothing to do with us. Any such messages that are not rejected at our SMTP port are trashed as they travel through our email system.