E-mail

Reading e-mail

E-mail may be read on the the departmental systems by either logging onto a UNIX machine and running, for example, pine or mutt, or by using the protocols IMAP or POP3 with arbitrary e-mail programs.

The relevant settings for IMAP (preferred) clients are:

• Server: mail.cs.umu.se
• Port: 993 with SSL (default SSL port)
• Username: your CS-username (for example id06abc)
• Password: your password

Sending e-mail

You must tell your client to use "authentication" / "secure authentication" or something similar when sending mail and specifying your account and username.

Configuration for outgoing mail via the departmental SMTP server:

• Server: mail.cs.umu.se
• Port: 587 with STARTTLS
• User name: your CS-username (for example id06abc)
• Password: your password

The mail server will only accept a message which has @cs.umu.se as the sender if it's sent from a computer in the department, or if the sending user has authenticated via the SMTP-server as described above.

The webmail project PUSS of ACC or our own webmail may also be used.

If the messages come from some outside source they are accepted in the same manner as described above. This applies consequently to to single messages which have a @cs.umu.se address as sender by come from outside of the departmental systems. This policy is implemented to limit incoming spam.

Address Book

In order to use LDAP for email addressing follow this guide.

Known problems

If person A has e-mail address xyz@somedomain.se (perhaps outside of our domain), but forwards a message automatically to personA@cs.umu.se and person B sends a message from personB@cs.umu.se to xyz@somedomain.se, the message will bounce with an indication that it cannot be delivered. In that case, the solution is to send the message directly to personA@cs.umu.se.

Spam, UCE, and viruses

All incoming e-mail is tested automatically for spam/UCE and viruses. AMaViS uses SpamAssassin to classify spam and Clam Antivirus to check for viruses. Viruses are removed; however, no other e-mail messages are removed using the classification provided by this program.

SpamAssassin classifies messages using a large number of tests which give "spam points" for each such test. If the number of points exceeds a predetermined threshold, the message is identified as spam.

ClamAV searches through the messages, unpacks possibly compromising attachments, and looks through them. If a virus is found, the message is so flagged.

To facilitate filtering, when a message is classified as spam, text indicating this is inserted into the message header.

Specifically the following header is inserted:

X-Spam-Flag: YES

To filter out such messages to an alternative mail folder, see below.

If you receive a message which is classified as spam, but is in fact not such, send a copy of all the headers to postmaster@cs.umu.se and we will whitelist the sender.

Since November 4,2003, blacklists have also been used for certain sending machines which prevent our server from accepting messages from them. These sending machines are, for example, misconfigured in such a way that spammers may easily use them as relays. The lists which are used currently are zen.spamhaus.org and dnsbl.njabl.org. More information may be found at http://www.spamhaus.org/zen and http://dnsbl.njabl.org. The message which one receives when a machine is blacklisted is:

554 5.7.1 UCE-09 Service unavailable; Client host [x.x.x.x] blocked using zen.spamhaus.org; http://www.spamhaus.org/query/bl?ip=x.x.x.x. Contact abuse@cs.umu.se if this is an error. 

Filtering

E-mail may be filtered for spam tagging by using (Pigeonhole) Sieve which is used to manage the final delivery.

For example, to direct that which AMaViS (see above) has classified as spam to another folder, insert the following code into ~/.dovecot.sieve:

require ["envelope","fileinto","mailbox"];
if header :contains "X-Spam-Flag" "YES" {
    fileinto :create "Spam";
    stop;
}

Afterwards, all messages which were classified as spam will wind up in the folder Spam.

Another method of adding this is to run Sieve plugin for Thunderbird. Under "View settings for this account" -> "Sieve settings":

• Server name: mail.cs.umu.se
• Port: 4190
• Authentication: Use login from IMAP Account
• User name: your CS-username
• Secure connection: true/TLS

(all of these should be default), then click Edit Filters.

A longer example is shown here:

# Sieve Filter

require ["variables","envelope","date","fileinto","mailbox","copy","regex"];

# Extract date info
if currentdate :matches "year" "*" { set "year" "${1}"; }
if currentdate :matches "month" "*" { set "month" "${1}"; }

# Archive items by year and month.
# Create folder when it does not exist.
fileinto :copy :create "archive_${year}_${month}";

if header :contains "From" "mamma@gmail.com" {
    # store in inbox, even if she's spamming you
    keep;
}
if header :contains "X-Spam-Status" "Yes" {
    fileinto :create "spam";
    stop;
}
if header :contains "X-Spam-Level" "*****" {
    fileinto :create "spam";
    stop;
}
if header :regex ["To","From","Cc"] "piraya.*@acc.umu.se" {
    fileinto :create "piraya";
    stop;
}
if header :contains ["To","From","Cc"] "mottagning06@ntk.umu.se" {
    fileinto :create "mottagning";
    stop;
}
if header :regex ["To","From","Cc"] ["c02.*@cs.umu.se","c02.*@acc.umu.se"] {
    fileinto :create "c02";
    stop;
}
if header :contains "Subject" "NTK veckomail" {
    fileinto :create "veckomail";
    stop;
}

Server software

The server software which we use is:

• Postfix
  • SMTP-daemons which send and received messages;
• Dovecot
  • IMAP/POP3-daemons which allow you to read mail from home; for example;
• Pigeonhole Sieve
  • The program which delivers incoming mail to your mailbox.
• AMaViS
  • Software for the management of scanning for viruses and classification of spam;
• SpamAssassin
  • Software which can classify spam;
• Clam Antivirus
  • Virus scanner
• Ecartis
  • Mailing-list management software used for the course mailing lists;