MailSSL

This module ensures SSL/TLS support for POP3/IMAP/SMTP. Configuration is practically identical to the configuration of the HTTP SSL module, but checking client certificates is not supported. 这个模块使得POP3／IMAP／SMTP可以使用SSL／TLS.配置已经定义了HTTP SSL模块，但是不支持客户端证书检测。

ssl

syntax:*ssl*on | off

default:*ssl off*

context:*mail, server*

Enables SSL/TLS for this virtual server. 在虚拟服务器中启用SSL／TLS

ssl_certificate

syntax:*sslcertificate**file_*

default:*cert.pem*

context:*mail, server*

Indicates file with the certificate in PEM format for this virtual server. The same file can contain other certificates, and also secret key in PEM format. 显示虚拟服务器上的PEM格式的证书文件。同一文件可以包含其他的证书和包含PEM格式的安全码。

ssl_certificate_key

syntax:*sslcertificate_key**file_*

default:*cert.pem*

context:*mail, server*

Indicates file with the secret key in PEM format for this virtual server. 显示虚拟服务器中PEM格式的安全码文件

ssl_ciphers

syntax:*sslciphers file**ciphers_*

default:*ALL:!ADH:RC4+RSA:+HIGH:+MEDIUM:+LOW:+SSLv2:+EXP*

context:*mail, server*

Directive describes the permitted ciphers. Ciphers are assigned in the formats supported by OpenSSL. 指令描述了容许的SSL chiphers.chiphers都被使用了OpenSSL支持的格式.

ssl_prefer_server_ciphers

syntax:*sslprefer_server_ciphers**on | off_*

default:*off*

context:*mail, server*

Requires protocols SSLv3 and TLSv1 server ciphers be preferred over the client's ciphers. 需要SSLv3协议,TLSv1 服务器端米阿么优先于客户端密码

ssl_protocols

syntax:*sslprotocols**[SSLv2] [SSLv3] [TLSv1]_*

default:*SSLv2 SSLv3 TLSv1*

context:*mail, server*

Directive enables the protocols indicated. 指令显示协议

ssl_session_cache

syntax:*sslsession_cache**[builtin[:size [sharedsize]_*

default:*builtin:20480*

context:*mail, server*

The directive sets the types and sizes of caches to store the SSL sessions. 指令设置了类型和存储SSL 会话的缓存的大小. The cache types are: 缓存类型为：

• builtin — the OpenSSL builtin cache, is used inside one worker process only. The cache size is assigned in the number of the sessions.builtin — OpenSSL内部缓存,这个只在内部工作进程中被使用.这个缓存大小等同于会话的个数。
• shared — the cache is shared between all worker processes. The size of cache is assigned in the bytes, 1 MB cache can contain about 4000 sessions. Each shared cache must have arbitrary name. Cache with the same name can be used in several virtual servers.shared — 这个缓存被所有工作进程共享.这个缓存大小用字节标识,1M缓存可以包含大约4000个会话。每个共享缓存都有专有的名称。相同名称的缓存可以被多个服务器使用。
  It is possible to use both types of cache simultaneously, for example: 可能同时使用2中类型的缓存，例如

ssl_session_cache  builtin:1000  shared:SSL:10m;

However, the only shared cache usage without that builtin should be more effective. 然而，共享缓存只有在内部缓存之外使用才能产生更好的效果。

ssl_session_timeout

syntax:*sslsession_timeout**time_*

default:*5m*

context:*mail, server*

Assigns the time during which the client can repeatedly use the parameters of the session, which is stored in the cache. 在使用中客户端重复使用的会话参数被存储在缓存中。

starttls

syntax:*starttls on | off | only*

default:*off*

context:*mail, server*

• on - permit the use of commands STLS for POP3 and STARTTLS for IMAP/SMTPon - 容许在POP3中的STLS命令和IMAP／SMPT中的STARTTLS命令
• off - do not allow command STLS/STARTTLS不容许 STLS／STARTTLS命令
• only - announce STLS/STARTTLS support and require that clients use TLS encryptiononly - 宣布支持 STLS／STARTTLS但是需要客户端使用TLS加密

原文: https://wizardforcel.gitbooks.io/nginx-doc/content/Text/5.4_mailssl.html