Email_Systems_Research.docx - Redmine

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30 Νοε 2012 (πριν από 5 χρόνια και 7 μήνες)

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Phil Lahman

Mail services

Imap and pop notes

Question? How are mail accounts on created or managed? Answer: With
Plesk control panel. (Need screen shots and more detail )

Question? Where are mail logs on Answer: /usr
/local/psa/var/log The file
maillog contains messages from qmail and courierimap.

Question? Where is account information for imap and pop mail accounts maintained?
Answer: /var/qmail/users. The assign file contains names. Need references to qmail
tion about accounts and password maintainence.


Programs in use for mail services


Mailman is free software for managing electronic mail discussion and e
newsletter lists.
It runs on GNU/Linux and most Unix
like systems
, and requires Python 2.1.3 or newer.
GNU Mailman works with Unix style mail servers such as Postfix, Sendmail and qmail.
Features include:

A Web browser interface for list administration, archiving of messages, spam

customizable home page for
each mailing list.

Integrated bounce detection and automatic handling of bouncing addresses.

Integrated spam filters

Multiple list owners and moderators.

list privacy features, such as closed
subscriptions, private archives, private
membership rost
ers, and sender
based posting rules.

Support for virtual domains.

Web based subscribing and unsubscribing. Users can temporarily disable their
accounts, select digest modes, hide their email addresses from other members, etc.

Horde Email Platform


a web
based email client.


a version of IMP utilizing AJAX
like technologies to allow a more dynamic
user experience.


a stripped down version of IMP for use on devices with a small screen or
limited HTML support such as mobile phones, PDAs and others.

Parallels Plesk Overview

Parallels Plesk Panel allows a server administrator to set up new websites, e
nts, and DNS entries through a web
based interface. The administrator can
create client and site templates, which predetermine resource allocation parameters
for the domains and/or clients.

Parallels Plesk Panel for Linux/UNIX supports multiple POSIX plat
includingDebian, Fedora, FreeBSD, Red Hat Linux, SUSE and Ubuntu. Parallels
Plesk Panel for Windows supports Windows Server 2003 and Windows Server
2008 operating systems.

Parallels Plesk Panel installs custom versions of or manages versions of MyS
and PostgreSQL databases (Microsoft SQL Server and Microsoft SQL Server
Desktop Engine under Windows), Apache Tomcat Java server


SpamAssassin is a computer program released under the Apache License 2.0 used
for e
mail spam filtering based

on content
matching rules. It is now part of the
Apache Foundation.

SpamAssassin uses a variety of spam
detection techniques, that includes DNS
based and checksum
based spam detection, Bayesian filtering, external programs,
blacklists and online database

The program can be integrated with the mail server to automatically filter all mail for
a site. It can also be run by individual users on their own mailbox and integrates
with several mail programs. SpamAssassin is highly configurable; if used as a
wide filter it can still be configured to support per
user preferences.

Methods of usage

SpamAssassin is a Perl
based) which is usually used to filter all incoming mail for
one or several users. It can be run as a standalone application or as a subpro
of another application (such as MailScanner) or as a client (spamc) that
communicates with a daemon (spamd). The latter mode of operation has
performance benefits, but under certain circumstances may introduce additional
security risks.

Typically eit
her variant of the application is set up in a generic mail filter program, or it is
called directly from a mail user agent that supports this, whenever new mail arrives. Mail
filter programs such as procmail can be made to pipe all incoming mail through
amAssassin with an adjustment to user's .procmailrc file.


SpamAssassin comes with a large set of rules which are applied to determine whether
an email is spam or not. Most rules are based on regular expressions that are matched
against the body
or header fields of the message, but SpamAssassin also employs a
number of other spam
fighting techniques. The rules are called 'tests' in the
SpamAssassin documentation. Each test has a score value that will be assigned to a
message if it matches the test
's criteria. The scores can be positive or negative, with
positive values indicating 'spam' and negative 'ham' (non
spam messages). A message
is matched against all tests and a SpamAssassin combines the results into a global
score which is assigned to the
message. The higher the score, the higher the probability
that the message is spam. SpamAssassin has an internal (configurable) score threshold
to classify a message as spam. Usually a message will only be considered as spam if it
matches multiple criteria
; matching just a single test will not usually be enough to reach
the threshold. If SpamAssassin considers a message to be spam, it can be further
rewritten. In the default configuration, the content of the mail is appended as a MIME
attachment, with a bri
ef excerpt in the message body, and a description of the tests
which resulted in the mail being classified as spam. If the score is lower than the defined
settings, by default the information about the passed tests and total score is still added
to the ema
il headers and can be used in post
processing for less severe actions, such
as tagging the mail as suspicious. SpamAssassin allows for a per
user configuration of
its behaviour, even if installed as system
wide service; the configuration can be read
from a

file or a database. In their configuration users can specify individuals whose
emails are never considered spam, or change the scores for certain rules. The user can
also define a list of languages which they want to receive mail in, and SpamAssassin

assigns a higher score to all mails that appear to be written in another language.

Mail transfer agent

A mail transfer agent (MTA) (also called a mail transport agent, message transfer
agent, or smtpd

(short for SMTP daemon), is a computer program or software agent
that transfers electronic mail messages from one computer to another.


An MTA receives mail from another MTA (relaying) or from a mail user agent (MUA).
The MTA works behind the sc
enes, while the user usually interacts with the MUA. One
may distinguish initial submission as first passing through a mail submission agent

formally, port 25 is used for communication between MTAs, or from an MSA to
an MTA, while port 587 is used
for communication between an MUA and an MSA;.
Every time an MTA receives an e
mail, it will add a "Received:" trace header field to the
top of the message. In this way, there is a record of which MTAs handled the e
mail and
in which order. Upon final deliv
ery, the "Return
Path:" header will also be added to
record the return path. The delivery of e
mail to a user's mailbox typically takes place via
a mail delivery agent (MDA); many MTAs have basic MDA functionality built in, but a
dedicated MDA like procmai
l can provide more sophisticated functionality.


qmail is a mail transfer agent that runs on Unix. It was written, starting December 1995,
by Daniel J. Bernstein as a more secure replacement for the popular Sendmail program.
qmail's source code is re
leased to the public domain, making qmail free software.

Mail Accounts and settings

SpamAssassin settings for WWW.SCTXCA.ORG at the global

Score for spam analysis 4.00 (default was 700

Subject to be modified with the information ****SPAM_SCORE_ *

Where SCORE is replaced with the actual spam score

Check for allow individual accounts and domains override global settings.

MAILMAN LISTS ACTIVE 3/18/09; rev. 5/14/09, 6/4/09

Address of list

password for admin access to change settings, approve
etc. These passwords are not needed to send messages to the list.

Names associated with each list are those who (in March 2009) had the Moderation
checkbox unchecked, so they could send messages to their list.

URL for access to the admin control
s for list listname:

Password will be requested for access to these
controls. Bruce Cottrill Chuck Fletcher Dick Smith Nancy Strayer Betty Steinke Gene Boley Peter Rol
l Joan Franklin Joan Keith Darrylin Coleman Ray Wright Nelda McQuary;

This list is still active but is not used; it contains the e
mail addre
sses only of Dick Smith
and Peter Roll.

mail accounts set up on the domain =;

with control panel settings;

Plesk Control Panel:
,, Home (left
> Mail icon
> Mail tab

Default settings:

email address

webmail on/ off (all on except Execboard)

control panel access on/off (All on except Execboard)

post box on/off (all on except execboard)

redirect on/off ( All off except as noted)

mailgroup on/off (All off except execboard and newsletter)

mail auto
responder on/off (all Off)

spamfilter on/off (all on)

antivirus scanning on/off (all Off)

ballroom2@sctxcompcl redir on


TO announce

P. Roll, 3/18/09; rev. 4/25/09; 6/4/2009 D. Willoughby

Adjusting Moderation for Specific Members:

First, set any existing subscribers (if there are any) so they're moderated:

Membership Management. Your current list of subscribers will be displayed.

At the bottom of the page, in the Additional Member Tasks,

set the Set everyone's
moderation bit, including those members not currently visible option to On.

Click the Set button.

Click the Submit button.

Scroll down the list of subscribers and uncheck the box in the Mod (first) column for
anyone who should be

authorized to send announcements to the list.

(If they're not
already subscribers, add them. For instructions, go HERE.)

Uncheck the Not metoo box for anyone who is authorized to send announcements
to the list, so that they will receive their announceme
nt and know that it was sent.

Click the Submit Your Changes button.

General Options:

Public name = name in e
mail address (before the @)

List administrator e
mail addresses: list at least one, on separate lines; this person
has authority and password t
o change the list settings

List moderator email addresses: none, lists are not moderated

Terse phrase..., An introductory description...,

: none

Prefix for subject line = name of list

Hide the sender of a message, replacing it with the list address Yes

Should any existing Reply
To: header found in original message be stripped? YES

Where are replies to list messages directed? Poster

all other radio buttons to bottom of page NO and text boxes empty,

Default options for new members joining this list =

checks only for Conceal..., Do
not send..., Filter out....; no check for Acknowledge...

Max. length in KB of mesage body = 500KB (max. total for msg+attachm
.) (can be
adjusted as needed; lists should not be used for distributing large or multiple

Host name this list prefers for email =

Should messages from this mailing list include the
RFC 2369

Discard held messages older than this number of days 0

Submit Your Changes button.

Digest Options:

Can subscribers choose to receive mail immediately, rather than in batched
digests? YE

No text in Header box

No text in Footer box

Scrub attachments of regular delivery message? NO

Submit Your Changes button

Digest Options: Digests should be disabled, as below:

Can list members choose to receive list traffic bunched in digests? NO

hich delivery mode is the default for new users? REGULAR

When receiving digests, which format is default? PLAIN

How big in Kb should a digest be before it gets sent out? 30 (default)

Should a digest be dispatched daily when the size threshold isn't reac
hed? NO

Header added to every digest empty box

Footer added to every digest empty box

How often should a new digest volume be started? YEARLY

Should Mailman start a new digest volume? NO

How often should a new digest volume be started? NO

Should Mail
man send the next digest right now, if it is not empty? NO

Submit Your Changes button

Privacy Options/Subscription Rules:

Advertise this list when people ask what lists are on this machine? No.

What steps are required for subscription? unsubscription

requests? YES

Banned address list none

Who can view subscription list? List admin only

Show member addresses so not directly recognizable as email addresses YES

Submit Your Changes button.

Privacy Options/Sender filters:

By default, should new list
member postings be moderated? Yes

Action to take when a moderated member posts to the list Discard

no text or lists in any of the boxes on this page

Action to take for postings from non
members for which no explicit action is defined

Should mess
ages from nonmembers, which are automatically discarded, be
forwarded to the list moderator? No.

Submit Your Changes button.

Privacy Options/Recipient filters:

Defaults are OK

Privacy Options/Spam filters:

Defaults are OK

Bounce Processing:

Defaults have Bounce processing enabled, with a bounce score set for each
member and notification of list
owner (admin) when bounce score gets high enough
to cause member to be disabled or unsubscribed. See text in this section for more

To disable b
ounce process: set 1st item

Should Mailman perform automatic bounce processing? = NO

Submit Your Changes button.

Archiving Options:

Defaults set Archiving ON, public, and Monthly. For announce
only lists we should
probably set

Archive? NO and


file source Private

Submit Your Changes button.

Mail <
> News Gateways:

Default is to disable such gateways


Responder: Defaults are NO


Content Filtering: Defaults are NO


Topics: Default for Topics filtering is Disabled



No person other than those authorized are able to send (post) a message to the list.

The mod checkbox next to their e
mail address in the list’s Membership must be
unchecked manually.

Persons authorized

to post messages to the list will receive copies of the message,
informing them that the message has been sent out to the list, because these
persons must be members of the list.

The not metoo checkbox next to their e
mail address in the list’s Membershi
p must be
unchecked manually if it is checked automatically.

All messages to the list are automatically discarded, with no notice to the sender.
This applies to postings sent to the list address and any messages to other list
addresses such as





No list moderators are designated, because no messages are moderated

they are
either accepted automatically because they come from authorized persons, o
r they
are discarded automatically and with no notice, because they come from persons
not authorized to post.

The List Administrator has nothing to do, except make any changes that may be
needed to the settings for the list. And this should not be neded,
once the list has
been tested in use and found to work properly.

The Mailman list software identifies persons authorized to post messages to the list
by their e
mail address as list members. Any messages sent to the list address that
spoof this address in the message header will be sent out to the list.

The only Comput
er Club list that deviates from the above requirements is the
mentors2 list. Because All members of the mentors group must be able to post
messages to this list. It is up to the leader and members of this list to monitor its
traffic and take whatever steps

are needed (including changing the name and
address of the list) if unauthorized postings occur in such numbers as to
compromise the list.