Chris Tyler - Fedora Linux

root: chris

Run the newaliases command after each edit to the /etc/aliases file to ensure that the changes are put into effect immediately:

# newaliases/etc/aliases: 76 aliases, longest 10 bytes, 765 bytes total

Next, change any aliases that you do not wish to redirect to root , sending the mail to the user of your choice:

info: sam

marketing: frida

sales: angela

support: henry

Destination mailboxes do not have to be local:

abuse: hotline@global.proximity.on.ca

And it's possible to specify multiple destinations for an alias, separated by commas:

webmaster: frank, jason@fedorabook.com

This opens up the possibility of using aliases to create simple mailing lists. For example, all of your sales people could be reached through one address:

sales-team: angela, sue, mike, olgovie, george

sysadmins: nancy43252345234@hotmail.com,

scott84353534534@gmail.com, george

Note that alias destinations can be on multiple lines.

You can create as many aliases as you want, whenever you want. Aliases are handy for creating disposable email addresses . I create batches of made-up addresses from time to time and use them when I register for a conference or web site, or when I enter a contest:

daa: chris

dab: chris

dac: chris

dad: chris

dae: chris

daf: chris

When I use one of these addresses, I record who I gave it to, and if I see spam arriving with that address, then I know who has been abusing my personal information. I can discontinue receiving mail at that address simply by removing the offending alias from the aliases file.

This strategy is also effective when publishing email addresses on a web site: simply change the address on the web site periodically, using a different disposable email address each time. If a spammer harvests your email address from the web page, it will be useful to them only for a short time.

Aliases (and regular user accounts) have one critical limitation: they apply to all of the domains for which sendmail is accepting mail. If you have a server that is accepting mail for fedorabook.com as well as global.proximity.on.ca , and you define an alias or create a user account named chris , then mail to chris@fedorabook.com and mail to chris@global.proximity.on.ca will end up in the same mailbox.

To overcome this limitation, use the /etc/mail/ virtusertable file to define where mail to each address should be sent. Each line in this file consists of an address, a space, and the destination. Here is an example:

chris@fedorabook.com chris

chris@global.proximity.on.ca chris7895378943683897@gmail.com

Note that the syntax for /etc/mail/virtusertable differs from the syntax for /etc/aliases : there are no colons, and only one destination address may appear in each entry.

virtusertable also permits the redirection of entire domains, by leaving out the username portion of the email address:

joe@fedorabook.com joseph

frank@fedorabook.com frank265897e93456738@hotmail.com

@fedorabook.com chris

The last entry will redirect all mail to the fedorabook.com domain to the local user chris , except for mail addressed to joe@fedorabook.com or frank@fedorabook.com (because they are listed first, and the file is processed in the sequence given).

Like /etc/mail/sendmail.mc , the virtusertable file must be processed before it is used:

# cd /etc/mail

# make

sendmail includes masquerading capability, which enables outbound mail to be modified so that it looks like it came from another system. This is commonly used to remove hostname information from the email address. To configure bluesky.fedorabook.com so that outbound mail appears to be from user @fedorabook.com instead of user @bluesky.fedorabook.com , locate the MASQUERADE_AS line in /etc/mail/sendmail.mc :

dnl # The following example makes mail from this host and any additional

dnl # specified domains appear to be sent from mydomain.com

dnl #

dnl MASQUERADE_AS(\Qmydomain.com')dnl

Uncomment the MASQUERADE_AS line and replace mydomain.com with the domain name you wish to use:

MASQUERADE_AS(\Q fedorabook.com ')dnl

Fedora's email system, like most others, is divided into three parts:

mail transport agent (MTA)

Transports mail between systems. sendmail is the default MTA.

mail delivery agent (MDA)

Delivers mail to local users, optionally performing filtering or sending vacation replies ("Jane is away from the office until Monday; she will read and reply to your mail when she returns"). Fedora uses procmail in this role.

mail user agent (MUA)

The email client that interacts with the user. A Fedora user can choose from many different MDAs, including Evolution, Thunderbird, SquirrelMail, and the text-based mail command.

Originally written when a wide range of email transportation schemes were in use, sendmail is designed to route mail through and between these different systems, each with their own address format and message queuing system. Because of this heritage, sendmail has a sophisticated and complex configuration system, but many of the configuration options are not used for Internet email servers.

sendmail is now used almost exclusively with the Simple Mail Transport Protocol (SMTP), which is a human-readable transfer protocol that uses TCP/IP connections on port 25. You can use telnet to connect to an SMTP server and manually send mail if you want:

$ telnet concord2.proximity.on.ca smtp

Trying 127.0.0.1...

Connected to concord2.proximity.on.ca (127.0.0.1).

Escape character is '^]'.

220 concord2.proximity.on.ca ESMTP Sendmail 8.13.5/8.13.5; Thu, 2 Mar 2006 13:07:11 -0500

EHLO fedorabook.com

250- concord2.proximity.on.ca Hello concord8.proximity.on.ca [127.0.0.1], pleased to meet you

250-ENHANCEDSTATUSCODES

250-PIPELINING

250-8BITMIME

250-SIZE

250-DSN

250-ETRN

250-AUTH DIGEST-MD5 CRAM-MD5

250-DELIVERBY

250 HELP

MAIL From: chris@fedorabook.com

250 2.1.0 chris@fedorabook.com... Sender ok

RCPT To: chris@concord2.proximity.on.ca

250 2.1.5 chris@concord2.proximity.on.ca... Recipient ok

DATA

354 Enter mail, end with "." on a line by itself

Subject: Greetings!Date: Thu, Mar 2006 12:08:11 -0500