Brief introduction of the application of SendMail in Enterprise Network (i.)

First, the basic knowledge:

1, Email Features:

1, fast;

2, safety;

3, diversity;

1, mail-related agreements:

Smpt Simple Mail Transfer Protocol application layer bottom walk TCP 25 plaintext

Pop pop/pop3 TCP 109/110 Clear text offline browsing messages

IMAP4 TCP 143 Online Browsing mail

Mime multiuser Mail Extension "HTTP Mail" can be transmitted by converting binary files into acsii code;

3, mail system

MUA: Mail user agent, generally refers to the mail client;

For example: window:outlook,foxmail;linux:mail,mutt,thunderbird;evolution

MTA: Message transfer agent, generally refers to mail server (sending server);

Window: E-mail Service, Exchange 2003 2007,mdaemon;

Linux:sendmail,postfix,qmail;

MDA: Mail Distribution Agent, Access Agent SendMail: Using procmail postfix: Using Dropmail

MAA: Mail access agent, generally refers to the receiving server;

Linux:dovecot "POP2/3 IMAP pop3s imaps"

4, the message security issues:

Ssl/tls

HTTP---HTTPS

POP3---pop3s

Lmap---imaps

5, the confidentiality of the message:

Smtp--smtps 465 Port

POP3---pop3s 995 port

Lmap---imaps 993 port

6, sendmail main configuration file

(1)/etc/mail/sendmail.cf:sendmail The main configuration file, manage all parameters. Because the syntax in SENDMAIL.CF is complex, do not recommend manual modification. Since we can use the SENDMAIL.MC document with the macros in the SENDMAIL-CF directory to automatically generate through the M4 preprocessor.

(2)/etc/mail/access.db:sendmail Server database, to be converted to this database requires MAKEMAP command and/etc/mail/access coordination

(3)/etc/mail/access: The host that sets which addresses can send and receive mail through a local sendmail server.

7, sendmial defects:

1, no authentication;

2, no garbage prevention;

3, no anti-virus;