Department of Physics and Astronomy - Computer Facilities

Using electronic mail in the Rutgers Physics Department

Introduction

All members of the Physics Department have email accounts on the Physics email system which uses addresses of the form "username@physics.rutgers.edu". Spam and virus filtering is provided, but some additional configuration by the user is necessary to take full advantage of the spam filter. See the section below on Spam filtering for further details on getting maximum use of the spam filter.

Reading email

The following options are available for reading email:

Use a mail reader program on your own computer that supports either the POP or IMAP protocols. Examples of such programs are Mozilla Thunderbird, Microsoft Outlook, and Evolution.
Use the Physics webmail system.
Use one of the email programs available on the Sun Unix cluster.

POP and IMAP

POP and IMAP are two protocols used to retrieve and manage email received on a central server. We support both, and choosing which one to use depends largely on personal preference. The basic idea of POP is to download all new messages from the mail server to your own computer and then delete them from the server. IMAP can do this, too, but it also allows you to create new mail folders on the mail server in which you can save messages. If you almost always use your own computer for email, then POP may be a good choice. If you use multiple computers, the additional flexibility of IMAP may be useful.

Your mail reader will offer you the option of choosing either POP or IMAP. The name of our POP server is pop.physics.rutgers.edu, and the name of our IMAP server is imap.physics.rutgers.edu. Enter one of these names where your mail reader requests "incoming mail server."

Our POP and IMAP servers both support SSL for encryption of the connection, but will also allow unencrypted connections. However, it is strongly advised to use SSL encryption, especially when connecting from outside of Rutgers.

Our IMAP server supports folders that contain sub-folders, but it does not support folders that contain both messages and sub-folders.

If your mail reader program has an "automatically subscribe to all folders" option, you should probably select that. However, note that this can cause very undesireable operation if you have not correctly specified the location of your mail folders.

Webmail

The Physics webmail system is available at http://webmail.physics.rutgers.edu. On that page you will find links to our two webmail systems, Squirrel Mail and Valencia Mail. We recommend Squirrel Mail, as the Valencia Mail system is no longer supported. However, some people prefer the Valencia user interface.

Sun Unix mail reader programs

In addition to the standard (and primitive) "Mail" program, the Sun Unix systems also have the Pine and Thunderbird programs, as well as the Sun-specific "dtmail" program.

Sending email

Sending email requires specifying the network name of a computer that will act as the server for outgoing mail. This is also called the "SMTP server". There are two cases to consider:

Sending email from a computer that will be used only at Rutgers
Sending email from a computer that will be used at least some of the time at remote locations

For computers that will be used only at Rutgers, the simplest configuration for outgoing email is to set the SMTP server to smtp.physics.rutgers.edu. Request use of port 25 (which should be the default), but do not request SSL or TLS encryption, nor session authentication.

For computers that are used at remote locations, the simplest configuration is to set the SMTP server to smtp.rutgers.edu. You must also request the use of SSL encryption and session authentication, and the port number must be set to 465. A username and password are required, and these are your Rutgers "NetID" username and password, not your Physics username and password.

Virus filtering

Both incoming and outgoing email are checked for computer viruses using the ClamAV system, and email containing a virus will be rejected. Also, the file extensions of all attachments are checked, and attachments with potentially dangerous extensions are deleted. If an extension is deleted, a warning message will be included in the email noting that a potentially dangerous attachment was deleted. Here is a list of the prohibited extensions:

      ade, adp, ani, app, asd, asf, asx, bas, bat, chm,
      cmd, com, cpl, crt, dll, exe, fxp, hlp, hta, hto,
      inf, ini, ins, isp, jse, lib, lnk, mdb, mde, msc,
      msi, msp, mst, ocx, pcd, pif, prg, reg, scr, sct,
      sh,  shb, shs, sys, url, vb,  vbe, vbs, vcs, vxd,
      wmd, wms, wmz, wsc, wsf, wsh

Spam filtering

All email is processed by the SpamAssassin spam checking system. This assigns a numeric score to each email -- the higher the score, the more likely the system considers the email to be spam. The email system will not accept email that receives a SpamAssassin score of greater than 15.0. However, as it is very likely that email with a score of 5.0 or greater is spam, users may want to enable additional spam filtering. The procedure to do this will be detailed below.

Headers added by SpamAssassin

SpamAssassin adds several headers to each email which can be used to assist in configuring spam filtering. Most mail readers are configured by default to show just a few header lines, so these additional headers will not be visible unless you enable the reader's "view full headers" option. Here are instructions for doing this with several popular mail readers. The headers added by SpamAssassin are as follows:

X-Spam-Checked: Spamassassin version 3.1.8, by Rutgers Physics
This is added to all email to verify processing by SpamAssassin on our server.
X-Spam-Score: N.N tests="list of tests"
"N.N" will be replaced by the actual spam score, and "list of test" will be replaced with a list of the SpamAssassin tests which contributed to the spam score.
X-Spam-Confidence: ****
This header will be included if the spam score is greater than 1.0. The number of asterisks will be equal to the integer truncated score.
X-Spam-Flag: YES
This header will be included if the spam score is greater than 5.0.

Options for spam filtering

It is recommended to quarantine all emails with a high spam score (usually, those above 5.0) into a "spam folder" that you can check periodically to look for "false positives". This way, your normal inbox will be almost spam-free. If you wish, you can also configure things so that email above a certain score threshold is simply deleted.

How you arrange for such filtering will depend on what kinds of computers you use, how you read your email, and your personal preferences. There are basically two options:

Use your mail-reader program to scan the spam headers and take appropriate action as it processes your mail. This is probably the simplest option if you use the POP mail protocol to read email.
Have the spam quarantined by the Physics Department mail system before it reaches your inbox. In this case, spam email will be saved to a folder in your mail directory on the Sun system (or, if you prefer, simply deleted). This is probably the option to choose if you read your email using the IMAP mail protocol or by logging onto the Sun system.

Spam filtering using your mail reader program

Since people use many different kinds of mail readers, it is impossible to give explicit directions, but basically the procedure is as follows. Open the menu item that allows you to set preferences or options, and look for features that allow you to 'filter' incoming email into mail folders.

The simplest method is to set up the filter to look for the header line

  X-Spam-Flag: YES

and save any email with that header to a specified folder (say, 'SPAM'). This will quarantine all of the spam with a spam score of 5 or more.

A slightly more complicated method is to set up the filter to look for a header line that contains the substring

  X-Spam-Confidence: *******

As explained above, the number of stars is the spam score; thus, the above setting would catch messages with a spam score of 7 or more. Using fewer stars will catch more spam, but increases the likelihood that a non-spam email will be caught incorrectly. (SpamAssassin is optimized to use a score of 5.0 as the demarcation point between spam and non-spam, which is why the "X-Spam-Flag: YES" is set at a score of 5.0.)

Spam filtering using the Physics Department mail system

To use this method, you will have to log in to one of the departmental Sun computers and execute a few commands under the Unix operating system. If you are not comfortable doing this, send an email to help@physics and request assistance. We will be glad to do the setup for you.

(Warning:If you ever use the Unix "vacation" program you will need to follow different instructions to use it after setting up spam filtering. Please follow this link for information on how to use the "vacation" feature after setting up spam filtering.)

Once you have logged in to the Sun computer system type the following at the command prompt:

  /physics/usr2/local/bin/configure_spamassassin

The script will ask you whether you want to do a 'simple' or 'custom', installation. In either case, it will create two files in your home directory, ".forward" and ".procmailrc" which together control the operation of the filter.

Simple installation: Mail with a score of 5.0 or higher will be quarantined to your spam folder.
Custom installation:
- Mail with a score 10.0 or greater will be DELETED.
- Mail with a score 1.0 or greater will have the Subject header modified to insert the string of stars from the 'X-Spam-Confidence:' header into the Subject header, yielding a result like this:
```
  Subject: ******* Great Stok Picks
```
- Mail with a score 5.0 or greater will be quarantined to your spam folder
By editing your .procmailrc file, you can easily adjust the two thresholds that are set by default at spam scores of 5 and 10.

It is a good idea to send yourself a test email after running the 'configure_spamassassin' script just to make sure that your email is still working correctly. In the unlikely event that it is not, delete the .forward ("rm ~/.forward) file and contact help@physics for assistance.

Checking your spam folder

If you normally read email after logging in to the Sun system, of the mail reader programs available there will allow direct access to your spam folder.

If you normally use a mail reader employing the IMAP protocol, you should find your spam folder listed along with your other mail folders.

If you normally use a mail reader employing the POP protocol, then you will not be able to use it to see your spam folder on the Sun system. Instead, use one of the departmental web-mail clients to read and clean up your spam folder.

Please send any comments on this page to

postmaster@physics.rutgers.edu

Last modified: Wednesday, March 19, 2008