如何使用sendmail配置企业简易邮件系统

如何使用sendmail配置企业简易邮件系统

企业邮件系统通常由三部分组成：邮件服务器、邮件客户端和邮件存储。邮件服务器负责接收和发送邮件，邮件客户端负责收发邮件，邮件存储负责存储邮件。

邮件服务器一般分为两类：POP3服务器和IMAP服务器。POP3服务器主要负责接收邮件，用户使用邮件客户端从POP3服务器下载邮件。IMAP服务器主要负责存储邮件，用户使用邮件客户端通过IMAP协议从IMAP服务器收发邮件。

sendmail是一个用于Unix/Linux平台的开源邮件服务器软件，可以作为POP3服务器或IMAP服务器使用。

下面介绍如何使用sendmail配置企业简易邮件系统。

首先，安装sendmail软件包，可以从官网下载安装包进行安装，也可以使用yum命令安装：

yum install sendmail

安装完成后，配置sendmail服务器。

打开/etc/mail/sendmail.mc文件，在dnl # Include the MC file generated by m4 above.dnl下面一行加入include(`/etc/mail/tls.mc')dnl，然后保存文件。

接下来，编辑/etc/mail/tls.mc文件，在dnl #### TLS Settingsdnl下面添加如下内容：

dnl #### TLS Settingsdnl

dnl # Use TLSv1dnl

define(`confUSE_TLS', `True')dnl

dnl # You need a certificate in /etc/pki/tls/certs and the matching key in

dnl # /etc/pki/tls/key. Make sure to generate it with:

dnl # make certreq && make sendmail-cert

dnl # Define these to use certificate in /etc/pki/tls/certs and key in

dnl # /etc/pki/tls/keydnl

define(`confSERVER_CERT', `/etc/pki/tls/certs/sendmail.pem')dnl

define(`confSERVER_KEY', `/etc/pki/tls/key/sendmail.pem')dnl

dnl # Trusted certificates. For CAs, place certificates in /etc/pki/tls/certs

dnl # and CRL in /etc/pki/tls/crldnl

define(`confCACERT_PATH', `/etc/pki/tls/certs')dnl

define(`confCACERT', `/etc/pki/tls/certs/ca-bundle.crt')dnl

define(`confSERVER_CERT_FINGERPRINTS', `/etc/mail/certs.md5')dnl

dnl # Client certificates. Place certificates in

dnl # /etc/pki/tls/certs and keys in /etc/pki/tls/keydnl

define(`confCLIENT_CERT', `/etc/pki/tls/certs/client-cert.pem')dnl

define(`confCLIENT_KEY', `/etc/pki/tls/key/client-key.pem')dnl

dnl # This defines who we trust and what CRLs we should check.dnl

define(`confTLS_SRV_OPTIONS', `V')dnl

dnl # This allows relaying if the user authenticates with POP or IMAP.dnl

define(`confTLS_PERM_CERT_FILE', `/etc/pki/tls/certs/ca-bundle.crt')dnl

define(`confTLS_PERM_CRL_FILE', `/etc/pki/tls/crl.pem')dnl

dnl # This defines who we trust and what CRLs we should check.dnl

define(`confTLS_SRV_OPTIONS', `V')dnl

dnl # This allows relaying if the user authenticates with POP or IMAP.dnl

define(`confTLS_PERM_CERT_FILE', `/etc/pki/tls/certs/ca-bundle.crt')dnl

define(`confTLS_PERM_CRL_FILE', `/etc/pki/tls/crl.pem')dnl

保存文件，然后重新编译sendmail配置文件：

m4 /etc/mail/sendmail.mc > /etc/mail/sendmail.cf

接下来，启动sendmail服务：

systemctl start sendmail

最后，设置sendmail服务开机自启动：

systemctl enable sendmail

配置完成后，sendmail服务器就可以使用了。