Reading email Forwarding email Sending email Spam filtering implementing SpamAssassin Virus protection Email recovery

Sending email

To send an email, a you need an email program that will communicate with CSIM email server.

It is defined as an AIT policy that in CSIM building, a user must go through CSIM email server to send and email to outside.

In the email program select mail.cs.ait.ac.th as the outgoing email server (SMTP):

Netscape Note the SSL/TLS connection whenever possible Note the incoming email server	Eudora

Encrypted email

CSIM email server has been enhanced with SSL/TLS encrypted connection. Whenever it is possible, the server will use encryption to talk to the user's client or to another server.

By using Netscape, and provided that the you have a certificate on your computer, encrypted communication can be established between Netscape and CSIM email server. In no case it guarantee that the email is encrypted from end to end, from the sender to the recipient, only connections that involve CSIM email server are concerned.

Email is send over the Internet by using SMTP (Simple Mail Transfer Protocol) where an enail is stored on an email gateway before it is sent to the next email gateway and repeating until it reaches the recipient.

Example of email transmission, with protocol used (SNMP or POP/IMAP)

In this case, the only transmission that can be encrypted are the green ones, between the sender and CSIM email server (provided he has a certificate), and between CSIM email server and the recipient email gateway (provided this gateway accepts encrypted connection). Encryption on other connections depends on email gateways that are not under CSIM management.

In any case, the connection only will be encrypted; when the email is stored on a gateway, it will be in plaintext/non-encrypted format. In order to assure an end-to-end encryption, the user should encrypt his message using PGP or GnuPG for example.

Roaming facility

Automatic and transparent roaming facility if provided to CSIM users. The solution that has been implemented is decribed bellow:

1. You authenticate to CSIM email server: this is done by reading incoming email, through POP or IMAP, using any of the authentication method described in the previous section.
   Hopefully, any email program will start by reading email, so authentication is the first step in using email program.
2. For the following 15 minutes, the machine that has authenticated is allowed to use CSIM email server to send outgoing email, even if it not located inside CSIM network.
3. Every time the user's email program automatically checks for new email (typically every 10 minutes), a new 15 minutes period is started.

Given that you haveauthenticated first, you can use CSIM email server without restriction. The setting of your email program needs not to be changed.

In order to reduce unsollicited commercial email (spam), CSIM email server has been set-up to refuse email relaying. It will only accept email with (green arrow):

• sender outise CSIM, and recipient inside CSIM;
• sender inside CSIM, and recipient outside CSIM;
• sender inside CSIM, and recipient inside CSIM.

But it will refuse any email when sender and recipient are outside CSIM (red arrow). When you are outside CSIM network (from home, travelling) and want to send email to a recipient that is also outside CSIM network, CSIM email server cannot be used.

With the roaming facility, you can use CSIM email server, after you have autheticated, but other machines cannot, so CSIM email server does not relay spam.

Next part: filtering spam.

Contact us: Olivier Nicole

Last update: Aug 2007