The following Q&A section describes the new services. If you are a MebTel customer, read the Q&A section for
e-mail users. If you want more technical details, or if you're having problems sending mail to a MebTel customer because of our new filtering services, please read the Q&A section for mail administrators.

E-MAIL USERS

Q: What new filters are being used?
A: MebTel uses blacklists provided by MAPS (Mail Abuse Prevention System) and Spamhaus.

Q: What are blacklists?
A: Both MAPS and Spamhaus maintain large lists of Internet addresses of known spammers, along with addresses of mail servers that are insecure and easily exploited by spammers. By rejecting mail from the mail servers listed in these blacklists, MebTel can greatly reduce the volume of spam that is sent to our customers.

Q: Do I need to do anything?
A: No! All the filtering is done on the MebTel mail servers, so you get the benefits of spam-filtered e-mail without having to make any changes to your computer.

MAIL ADMINISTRATORS

Q: Can you give me more technical details about the MAPS and Spamhaus services used by MebTel?

A: Sure. MebTel subscribes to the MAPS RBL+ service, which contains the following lists:

Realtime Blackhole List (RBL): Sites on this list include sites that may be an open relay, a spam source, or a spam support service.

Relay Spam Stopper List (RSS): Sites on this list are open relays and can be easily exploited by spammers who wish to conceal their identity.

Dial-Up User List (DUL): Sites on this list contain IP addreses that are in dial-up netblocks. These blocks are often dynamically assigned and dial-up customers should be using their ISP's mail server to send mail instead of running their own mail server.

MebTel also subscribes to Spamhaus' SBL list, a large list of IP addresses of verified spam sources.

MAPS: http://mail-abuse.org
Spamhaus: http://www.spamhaus.org

Q: Help! I tried to send mail to a MebTel customer, but got a message back that said:

554 Service unavailable; Client host [xxx.xxx.xxx.xxx] blocked using rbl-plus.mail-abuse.org;

or

554 Service unavailable; Client host [xxx.xxx.xxx.xxx] blocked using sbl.spamhaus.org;

What do I do?

A: Your mail server (or your ISP's mail server) has been placed on either the MAPS blacklists (in the first example) or Spamhaus' blacklist (in the second example). This is either because MAPS/Spamhaus believe your mail server is a known source of spam, or because your mail server is an open relay.

Q: What is an open relay?
A: A well-configured mail server should only allow certain people to use it for sending mail (e.g. customers). Older or poorly-configured mail servers, however, allow anyone to send mail using the server. This is known as an "open relay", and is considered very bad since any spammer can use the server to send e-mail that is virtually untraceable.

Q: So how can I get my mail server (or my ISP's mail server) off the blacklists?
A: You (or your ISP) will need to contact either MAPS or Spamhaus to have your mail server's IP address removed from their blacklists. If you've gotten onto the MAPS blacklist, visit the "How Can I Fix The Problem?" page. If you've been blocked by the Spamhaus blacklist, visit the "SBL Removal Requests" page.