FOR IMMEDIATE RELEASE

Stalker Software Announces Stalker Internet Mail Server 1.6

Key features: New Blacklisting (RBL) implementation, support for mobile
users, still FREE

MILL VALLEY, CA - April 22th, 1998 - Since the first free public release of
Stalker's Internet Mail Server, it has been consistently upgraded with new
performance enhancements. The most recent public version to be released
1.6, offers the latest technologies for mail servers including anti-spam
features and better administrative additions.

IP Blacklisting has been proven to be the most efficient way to cut
unsolicited E-mail ("spam") messages: mail servers with IP blacklisting
implemented rejects all messages that come from known offenders. However,
spammers may change their providers and IP addresses, and new spammers
appear every week. This makes the job of keeping the Black List current an
everyday duty for mail server administrators.

The DNS-based blacklisting is a new emerging technology that automates this
task. A regular DNS server located anywhere on the Net can be used to keep
the IP addresses of all known spammers. The anti-spam warriors inform the
administrator of the black-listing server about unsolicited E-mail their
users have received, so that the server has an up-to-date list of known
offenders.

With the 1.6 version of SIMS, the name of a black-listing server can be
entered in the SMTP module settings. When SIMS receives mail from a remote
host, it checks not only its own black list, but also consults the black-
listing server, too. If the sending host is included in the blacklisting
DNS server tables, messages from that host are not accepted. The entire
process is automatic and allows all mail server administrators to
centralize and to distribute their knowledge about offending sites. Since
the blacklisting servers are implemented using the existing DNS technology
and software, several servers are already available on the Net, and they
can be used with any SIMS 1.6 mail server.

One of the first anti-spam features implemented in SIMS was protection from
unauthorized mail relaying. SIMS could relay a message to any Internet site
only if it was sent from a known (usually - LAN) IP address. This feature
did not allow spammers to abuse a SIMS server, but it also created problems
for mobile users that connected to the Internet via various providers, and
thus used various IP addresses. These mobile clients could not use SIMS as
their "SMTP server". With the version 1.6 this problem is addressed in two
ways.

First, the so called "XTND XMIT" extension is implemented in the POP
module. It allows remote users to submit messages via the POP, not SMTP
protocol, and the POP3 protocol authenticated users using passwords, not IP
addresses. Eudora and some other mailers support this POP protocol
extension.

Second, the POP module records the client IP address when it authenticates
a user. During the next minute, messages from that IP address are processed
as messages from the known (LAN) clients. When remote users check their
mail on the SIMS server (this results in user authentication), their IP
addresses are recorded. Then they submit messages to the server via the
regular SMTP protocol. Since the messages come from the authenticated
addresses, they are marked as such and can be relayed anywhere.

Along with the new Anti-spam features, SIMS has been updated with several
enhancements for Administrators, thus allowing for easier monitoring of the
server. The SIMS logs now receives a Failure (Level-1) record when the SMTP
module rejects a return-path or a recipient address, and a when the POP or
PWD module rejects a user name/password: this feature allows administrators
to detect when their systems are under attack.

PRICING and AVAILABILITY: Stalker Internet Mail Server is available free of
charge. The software can be downloaded from:
(http://www.stalker.com/SIMS/), (ftp://ftp.stalker.com/) and Stalker mirror
sites overseas.

DOCUMENTATION: the entire SIMS System Guide can be used via the Internet at
( http://www.stalker.com/SIMS/), and it can be downloaded for local use
from the same SIMS site.

SUPPORT: Stalker Software has an active list (sims@stalker.com) mailing to
discuss the SIMS issues. With 50+ messages per day and several hundred
subscribers, this list provides immediate technical support assistance both
from the Stalker support staff and experienced SIMS administrators.
Subscription requests should be sent to (sims-on@stalker.com), and the
digest- mode subscription can be requested at (sims-digest@stalker.com)

All product names are trademarks or registered trademarks of their
respective manufacturers.

Stalker Software, Inc. develops and distributes networking and
communication software for the MacOS. The company was founded in Europe in
1991 and opened its U.S. offices in 1993 at 655 Redwood Highway, suite 275,
Mill Valley, Calif. 94941. For more information about Stalker Software and
its products, please contact Ali Liptrot, director of sales and marketing,
at (800) 262-4722 or (415) 383-7164, fax to (415) 383-7461, or E-mail at
(ali@stalker.com). Visit the Stalker Software web site at
(http://www.stalker.com).