个人总结:
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讲解了跟电子邮件有关的三个协议:
SMTP（simple message transfer protocol 简单信息传输协议
IMAP （internet message access protocol 互联网信息获取协议
POP3 (post office protocol version3 邮局协议v3
SMTP允许发送邮件到邮件服务器 （发送邮件
IMAP和POP3从邮件服务器拉取邮件，IMAP有同步、归档等功能，POP3则没有同步的功能 （拉取邮件
资料一:
三个和email有关的协议:
SMTP simple message transfer protocol:
allow you to send out a message to your internet server
through route to its destination, once it arrives destination
it stored on that mail server until a email client grabs it.
and the two major methods of grabbing that are
IMAP:
Internet Message Access Protocol
(its nice synchronizing two or more applications.
if you have a Blackberry or a Iphone or serveral computers
and you want to read the same message across the board then
IMAP is the system for u.
IMAP allows you to organize a hierachy of messages
so you can have your inbox and then below your inbox
you can have modify folders, sothat all your clients
will get the change of your folders.
if you dont use hierachy organize, pop3 may be better.
if one message you marked as read, all your clients will
show its read.(its all about synchronize
and POP3:
Post Office Protocol Version 3(Quick and simple
资料二:
POP3"
it doesnt download any other folders or their contents,
so it doesnt download your sent items, your drafts,your deleted mail...
and it doesnt do any synchronization
所以可能会造成这样的问题,新的邮件来了，上面的收到了，但是下面的收不到了，(因为服务器发给上面的客户端后就删除掉了
然而很多客户端会有一个 leave a copy on the server 选项，防止这种问题发生
IMAP:
如果删除的时候就是向服务器发请求 然后其他客户端会sync
实际客户端使用的时候是可以配置的:
或..
优缺点:
pop3
(因为已经下载到客户端了
IMAP:
(然而 有一些客户端会有下载到本地 而不是 just caching 的功能
资料三:
POP、IMAP tells where email from
SMTP tells where email to