[root@www ~]# cd /etc/pki/tls/certs[root@www certs]# make server.keyumask 77 ; \
/usr/bin/openssl genrsa -aes128 2048 > server.keyGenerating RSA private key, 2048 bit long modulus
......................................................++++++
.............++++++
e is 61251 (0x10001)
Enter pass phrase:# set passphraseVerifying - Enter pass phrase:# confirm# remove passphrase from private key[root@www certs]# openssl rsa -in server.key -out server.keyEnter pass phrase for server.key:# input passphrasewriting RSA key
[root@www certs]#
[root@www certs]# make server.csrumask 77 ; \
/usr/bin/openssl req -utf8 -new -key server.key -out server.csrYou are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
-----
Country Name (2 letter code) [XX]:JP
# countryState or Province Name (full name) [e]:Hiroshima# stateLocality Name (eg, city) [Default City]:Hiroshima
# cityOrganization Name (eg, company) [Default Company Ltd]:GTS# companyOrganizational Unit Name (eg, section) []:Server World# departmentCommon Name (eg, your server's hostname) []:www.srv.world# server's FQDN

Email Address []:xxx@srv.world
# email addressPlease enter the following 'extra' attributes
to be sent with your certificate request
A challenge password []:# EnterAn optional company name []:# Enter[root@www certs]#
[root@www certs]# openssl x509 -in server.csr -out server.crt -req -signkey server.key -days 3650Signature ok
subject=/C=JP/ST=Hiroshima/L=Hiroshima/O=GTS/OU=Server World/CN=www.srv.world/emailAddress=xxx@srv.world Getting Private key
[root@www certs]# chmod 400 server.* 

[root@mail ~]# vim /etc/postfix/main.cf
# 添加到最后
smtpd_use_tls = yes
smtpd_tls_cert_file = /etc/pki/tls/certs/server.crt
smtpd_tls_key_file = /etc/pki/tls/certs/server.key
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache
smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
smtpd_tls_loglevel = 0
smtpd_tls_auth_only = yes[root@mail ~]# vim /etc/postfix/master.cf
# 17-18行: 取消注释
smtps       inet   n       -       n       -       -       smtpd-o smtpd_tls_wrappermode=yes[root@mail ~]# vim /etc/dovecot/conf.d/10-ssl.conf
# 6行: 取消注释
ssl = yes
# 12,13行: 指定证书
ssl_cert = </etc/pki/tls/certs/server.crt
ssl_key = </etc/pki/tls/certs/server.key
#开放SSL端口(端口的话，SMTP使用的是465, POP3使用995, IMAP使用993)firewall-cmd --add-port={465/tcp,995/tcp,993/tcp} --permanentfirewall-cmd --reload
# 重启postfix
[root@mail ~]# systemctl restart postfix
Shutting down postfix: [ OK ]
Starting postfix: [ OK ]# 重启dovecot
[root@mail ~]# systemctl restart dovect
Stopping Dovecot Imap: [ OK ]
Starting Dovecot Imap: [ OK ]