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SmarterMail in Individual and Micro-business Deployments
Who Should Use This Document
This document is intended for use by individuals and micro-businesses as they develop
an effective architecture for their SmarterMail system implementation. For best
results, this document should be used in conjunction with the SmarterTools Knowledge Base.
Determining the Required Architecture
It is not unusual for a business to generate upwards of 50 legitimate mail messages,
per employee, per day on average1. Considering the relative volume of
spam and other abusive messages that are currently prevalent, the total number of
messages processed per user/mailbox could easily exceed 250 per day2
. Companies in technology, finance, and other communication-intensive industries
might have much higher average email volumes. A tendency toward the prolific use
of attachments and email graphics can also influence performance in mail environments.
SmarterTools encourages readers to determine which architecture is right for them
based upon anticipated email volume as opposed to head-count because email load
is a far better predictor of server requirements than the number of mailboxes on
a system.
SmarterMail is built around a fully scalable model, so moving from one architecture
recommendation to another requires relatively simple enhancements or modifications
that can yield significant increases in performance and volume capacity.
That said, the authors have chosen to divide their recommendations into three categories:
individual and micro-business architectures, small to medium-sized business architectures,
and high-volume deployment architectures. For the purposes of these recommendations:
- Individuals and micro-businesses shall be defined as mail environments with average
email volumes of up to 25,000 messages per day (12,500 in/12,500 out). This infers
a maximum of 100 mailboxes. Information regarding these architectures
is available in this SmarterTools document.
- Small to medium-sized businesses shall be defined as mail environments with average
email volumes of up to 400,000 messages per day (200,000 in/200,000 out). This infers
a maximum of 1,600 mailboxes. Information regarding these architectures
can be found in SmarterMail in Small to Medium-sized Business Deployments,
which is available for download on the SmarterTools website.
- High-volume deployments shall include ISPs, hosting companies, large businesses,
and enterprise organizations with average email volumes numbering in the millions.
This infers organizations with many thousands of mailboxes. Information
regarding these architectures can be found in SmarterMail in High-Volume Deployments,
which is available for download on the SmarterTools website.
1Intel presentation, “IT Business Value”, 9-16-2005.
2Nearly 80% of email messages sent world-wide are spam….”; Deleting
Spam Costs Business Billions, Information Management Journal, May/June 2005, Nikki
Swartz
General Architecture
The general recommendation for SmarterMail architecture in an individual and micro-business
environment (up to 25,000 messages per day) is as shown in Figure 1.
SmarterMail Primary Server
This server is the central data processor and repository of your client’s email.
Users connect to this server using POP and IMAP to receive email, and use SMTP to
send email out. Webmail is also hosted on this server to help those without email
client software. In addition, the SmarterMail server performs all spam-blocking
and virus protection operations.
Hardware recommended in this configuration for individuals and micro-businesses
includes:
- Single-core processor
- 1 GB of RAM
- Windows Server 2008 R2 64-bit
- 7200 RPM SATA drive
Email Virtualization: SmarterMail in Virtual Server (VPS) Environments
A virtual server environment is when one physical hardware device is partitioned
so as to operate as two or more separate servers. SmarterMail can be deployed in
all types of virtual server environments and has been tested with most major virtualization
software (such as Hyper-V, VMware, Virtual Box, Virtuozzo and Zen).
Note: If using Hyper-V, SmarterTools recommends attaching a physical network adapter
from the Hyper-V host to the SmarterMail virtual machine instead of using the virtual
network manager to create virtual LANs/bridges. This is because there is a risk
of losing network access to all of the virtual machines if they are all tied to
a single virtual network and a network-related issue occurs on one of the virtual
machines. By allowing the SmarterMail virtual machine a dedicated physical connection,
this risk can be eliminated.
Recommended Spam Protection Measures
SmarterMail uses a flexible, multi-layered spam prevention strategy to achieve 97%
spam protection out-of-the-box. Initial spam settings are configured during installation,
but system administrators can modify these settings to meet their unique needs at
any time.
Since spam prevention strategy is an integral component of mail server deployment,
a few of the most important spam-fighting measures available for SmarterMail are
discussed below.
Cyren (formerly Commtouch) Premium Antispam
Available as an optional add-on for SmarterMail, Cyren Premium Antispam uses
Recurrent Pattern Detection (RPD) technology to protect against spam outbreaks in
real time. Rather than evaluating the content of messages, the Cyren Detection
Center analyzes large volumes of Internet traffic in real time, recognizing and
protecting against new spam outbreaks the moment they emerge. When combined with
SmarterMail’s out-of-the box antispam measures, the Cyren Premium Antispam add-on
can effectively block 99.5% of spam from users’ inboxes.
For more information about the Cyren Premium Antispam add-on, please visit the
SmarterTools website.
SpamAssassin-based Pattern Matching Engine
SmarterMail incorporates the SpamAssassin-based Pattern Matching Engine as part
of its multi-layered spam protection strategy. Based on SpamAssassin technology,
this powerful pattern matching engine can process substantially higher volumes of
email per day without the need for a distributed antispam server. For more information,
please refer to the SmarterMail Online Help.
Greylisting
SmarterMail also includes greylisting, an effective method of blocking spam at the
SMTP level. Using the greylisting feature in conjunction with SpamAssassin will
prevent a large percentage of spam messages from being received by the SmarterMail
server and drastically reduce the SpamAssassin work load. At the time of this writing
the greylisting feature is effectively blocking up to 85% of spam at the SMTP level
and greatly enhancing the effectiveness of SpamAssassin. The authors expect that
the effectiveness of greylisting will diminish over time as spammers learn to adjust
to this technique. Additional information about greylisting can be found in the
SmarterMail Online Help or at http://greylisting.org.
Other Built-in Antispam Measures
SmarterMail’s multi-layered spam prevention strategy also includes SPF, DomainKeys/DKIM,
Bayesian filtering, reverse DNS, RBL, blacklist/whitelist, SMTP blocking, custom
headers, and per-user spam weighting. More information about these important features
is available in the SmarterMail Online Help and/or the SmarterTools Knowledge Base.
Remote SpamAssassin
SmarterMail includes support for SpamAssassin, an open source spam filtering program.
When implemented, SmarterMail will pass an incoming message to SpamAssassin. SpamAssassin
returns the message with a spam score that can be used to filter
mail alone or in conjunction with other spam filtering options
in SmarterMail.
The Windows version is limited to processing a single message at a time—effectively
handling approximately 25,000 spam messages per day. This version of SpamAssassin
is usually more than adequate to meet the needs of individual and micro-business
environments. Additional information about SpamAssassin, including download instructions,
is available at http://spamassassin.apache.org.
Recommended Virus Protection Measures
SmarterMail includes several antivirus enhancements that prevent the mail server
from being compromised, including support for incoming and outgoing SSL/TLS connections,
administrator access restriction by IP, intrusion detection (IDS), active directory
authentication, harvest attack detection, denial of service (DOS) attack prevention,
malicious script authentication, and brute force detection for webmail.
Cyren (formerly Commtouch) Zero-hour Antivirus
Available as an optional add-on for SmarterMail, Cyren Zero-hour Antivirus can
further extend SmarterMail’s built-in virus protection measures. Rather than depending
on heuristics, Cyren Zero-hour Antivirus uses Recurrent Pattern Detection (RPD)
technology to scan the Internet and identify virus and malware outbreaks as soon
as they emerge.
For more information about the Cyren Zero-hour add-on, please visit the SmarterTools
website.