1) Mail user agent (Mail user agent , mua), MUA is a mail system client program that provides a user interface for reading, sending, and receiving e-mails. Most commonly used MUA has: linux mail , elm , pine and so on. Windows outlook , foxmail et 2) mail agent ( mail transfer agent , MTA ) MTA responsible for the storage and forwarding of messages ( store and forward ). MTA Monitor the user agent's request, locate the corresponding mail server based on the destination address of the e-mail message, transfer the letters between the servers and buffer the received messages. MTA programs under linux have: sendmail , qmail , 3) Mail Submission agent ( mail Submmission Agent , MSA ) MSA responsible for all the preparation and error detection that must be done before the message has MTA send MSA is like inserting a sober-minded inspector between MUA and MTA to detect all of the host names and the information first-class information that is obtained from MUA . 4) Mail delivery Agent ( Mail Ddlivery Agent , MDA ) MDA from MTA Receive the message and make the appropriate local delivery, you can post a local user, a mailing list, a file or a program. Linux Common MDA is &NBSP;MAIL.LOCAL&NBSP;,&NBSP;SMRSH&NBSP, and procmail ( www.procmail.org ) 5) Mail access agent (&NBSP;MAIL&NBSP;ACCESS&NBSP;AGENT&NBSP; MAA ) MAA is used to connect users to the System mail library, using POP or IMAP protocols to receive messages. Linux Common MAA has UW-IMAP , Cyrus-IMAP , COURIER-IMAP and so on Mail relay: is when the message is transmitted to the destination address, once the source and destination addresses are not local systems, the local system is the trunk of the message (the broker). mua the user communicates with the mail server through this program, including receiving ( POP3 connecting the recipient Server program &NBSP;IMAPD) or sending a letter (smtp connection mta), for example: Outlook express ... such as mta use the SMTP protocol to pass letters to different mail hosts, for example: sendmail, postfix, qmail ... such as msa is the client end agent for the new sendmail development to SSMTP TLS/SSL online. mda the letter is sent to different user mailboxes, is a MTA subsystem, such as BBS is defined as &NBSP;MDA ( BBS function Complex, Of course not only mda), some MDA are designed to do filter action, they have to operate at the local end, and therefore called lda, for example: procmail ... such as mailbox e-mail that has not yet been downloaded by the user, will temporarily exist in the server's hard disk space, called the mailbox. All user mailboxes must be approximately equal to half the total capacity of the partition to avoid space in the mailbox but the messaging system is not workingThe phenomenon. mail gateway is a special kind of mail server, which usually plays the role of agent, which is responsible for coordinating the sending and receiving of all correspondence in an organization, and distributing the mail to the subordinate's mail server, which can speed up the exchange of mails and can carry out consistent filter control. SendMail is a Linux system in a mailbox system, if we configured in the system SendMail can be used directly to send mailboxes.
Configuration file for SendMail
/etc/mail/sendmail.cf:sendmail master configuration file;/etc/mail/access: Relay access control;/etc/mail/domaintable; domain name Mapping;/etc/mail/ Local-host-names;/etc/mail/mailertable: Specifies a special routing rule for a specific domain;/etc/mail/virtusertable: virtual domain configuration.
Configuration of Trunks
means that a server accepts and passes messages that are not the source and destination addresses of the server. Set in two files:/etc/mail/relay-domains/etc/mail/access.
First, install the software
[email protected] ~]# yum install-y sendmail[[email protected] ~]# yum install-y sendmail-cf
Start the SASLAUTHD service for SMTP authentication (installed by default, if not, install manually)
[[Email protected] ~]# service SASLAUTHD startstarting SASLAUTHD: [OK]
Second, the Mail service configuration
1) Configure Senmail SMTP Authentication to remove the DNL in front of the following two lines of content. In the SendMail file, DNL indicates that the behavior comment line is invalid, so you can open the corresponding setting line by removing the DNL string at the beginning of the row. [[EMAIL&NBSP;PROTECTED]&NBSP;~]#&NBSP;VIM&NBSP;/ETC/MAIL/SENDMAIL.MC ...] Trust_auth_mech (' External digest-md5 cram-md5 login plain ') dnldefine (' ConfAUTH_MECHANISMS ') , ' External gssapi digest-md5 cram-md5 login plain ') dnl2) Set the network access permissions for the SendMail service (if it is a direct native call, you can use the default 127.0.0.1 instead of the operation.) But eventually it changed to 0.0.0.0. Change 127.0.0.1 to 0.0.0.0, meaning that any host can access the SendMail service. If only one segment is allowed to access the SendMail service, change 127.0.0.1 to a specific segment address that is shaped like 192.168.1.0/24. [[EMAIL&NBSP;PROTECTED]&NBSP;~]#&NBSP;VIM&NBSP;/ETC/MAIL/SENDMAIL.MC ...] Daemon_options (' Port=smtp,addr=0.0.0.0, name=mta ') dnl3) generate configuration file SendMail configuration file is generated by M4, M4 tool in SENDMAIL-CF package. If the system does not recognize the M4 command, it indicates that the SENDMAIL-CF package is not installed [[email protected] ~]# m4 /etc/mail/sendmail.mc > &NBSP;/ETC/MAIL/SENDMAIL.CF4) Start Service [[email protected] ~]# service sendmail Startstarting sendmail: [ ok ]starting sm-clienT: [ ok ][[email protected] ~]# service saslauthd restartstopping saslauthd: [ ok ]starting saslauthd: [ ok ] Join the service in the self-starter row [[email protected] ~]# chkconfig sendmail on[[email protected] ~]# chkconfig Saslauthd on[[email protected] ~]# chkconfig --list |grep sendmailsendmail 0:off 1:off 2:on 3:on 4:on 5:on 6:off[[email protected] ~]# chkconfig --list |grep saslauthdsaslauthd 0:off 1:off 2:on 3:on 4:on 5:on 6:off
Third, test send mailbox
(1) The first way: the installation of SendMail can be used. [[email protected] ~]# yum-y install MAILX Create a message content file, and then send the message (note that the-s parameter after the message header to use single quotation marks, cannot use double quotation marks, otherwise the email will fail!) ) [[email protected] ~]# echo ' This was test mail ' >/root/content.txt [[email protected] ~]# Cat/root/content.txt this is Test Mail[[email protected] ~]# mail-s ' Test Mail ' ******@163.com </root/content.txt view Received message:
If you do not want to send a message through a file, you can send it, or you can use the pipe character to send the message directly, the effect is the same as the file sent the message content.
[Email protected] ~]# echo "This is Test mail." | Mail-s ' Mail Test ' ******@163.com
View received messages:
If you are sending to multiple messages, use the-c parameter, as follows:
[Email protected] ~]# echo "This is Test mail" | Mail-s ' test '-c ****** @sina. com ******@163.com
(2) The second way: the use of external smpt server in the first way, the/bin/mail command will default to use local sendmail send mail, which requires the local machine must install and start the SendMail service, configuration is very cumbersome, and will bring unnecessary resource consumption. By modifying the configuration file, you can use an external SMTP server to send mail with an external SMTP server without using SendMail. Modify the/etc/mail.rc file (some version is called/etc/nail.rc, add the following content:set [email protected] smtp=smtp.domain.comset Smtp-auth-user=username smtp-auth-password=passwordset smtp-auth= Login parameter Description: The From is the address of the outgoing SMTP server to which the mail address SMTP is occurring smtp-auth-user is the external SMTP server authenticated user name. Note Be sure to fill in the full name of the message!! Smtp-auth-password is the external SMTP server authentication user password Smtp-auth is the way the message authentication is configured, you can send the message normally, as follows [[email protected] ~]# vim /etc/mail.rc //add set firstname.lastname@example.org smtp= at the bottom of the file Smtp.3dmedcare.com email@example.com smtp-auth-password=3dmed123 smtp-auth= Login now starts sending mail:[[email protected] ~]# echo "Hello world" |mail -s " test666 ' ****[email protected]
Linux SendMail mail system installation operation record