MX查找返回的确切地址是什么？ [英] What addresses are exactly, returned by MX lookup?

问题描述

正在寻找一种通过Python代码发送电子邮件的方法，但我偶然发现了以下内容：

当我使用 host -t mx gmail.com 命令（我从这个答案），我得到以下信息：

While searching for a way to send an email from Python code, I have stumbled upon the following:
when I am doing an MX lookup with host -t mx gmail.com command (which I've "borrowed" from this answer), I am getting the following:

gmail.com mail is handled by 5 gmail-smtp-in.l.google.com.
gmail.com mail is handled by 30 alt3.gmail-smtp-in.l.google.com.
gmail.com mail is handled by 20 alt2.gmail-smtp-in.l.google.com.
gmail.com mail is handled by 10 alt1.gmail-smtp-in.l.google.com.
gmail.com mail is handled by 40 alt4.gmail-smtp-in.l.google.com.

在官方gmail文档（其中有： smtp-relay.gmail.com ， smtp.gmail.com ， aspmx.l.google.com ）。我的理解是MX查找应该返回服务器（或其中的列表）的地址，该地址负责处理域中的邮件。

Non of this servers are mentioned in the official gmail docs (the ones that are there: smtp-relay.gmail.com, smtp.gmail.com, aspmx.l.google.com). My understanding was that MX lookup should return address of the server (or list of them), which is responsible for handling mails for the domain.

我的问题是：

1. 为什么文档中提到的smtps都不由MX查找返回？


2. 哪些服务器是MX查找返回的邮件？


3. MX查找返回的服务器是否可以用于将电子邮件发送到域电子邮件（在这种情况下为gmail）？


4. 可以使用MX查找返回的服务器将电子邮件发送到任意域的电子邮件吗？


5. 如果对前面两个问题中的任何一个回答为是，则必须进行身份验证服务器？

1. Why none of the smtps mentioned in the docs are returned by MX lookup?
2. Which servers exactly are returned by MX lookup?
3. Can servers returned by MX lookup be used to send an email to the domain emails (gmail in this case)?
4. Can servers returned by MX lookup be used to send an email to an arbitrary domain email?
5. If answer is "yes", to any of two previous questions — what authentication is required to use these servers?

推荐答案

用一些外行的话来说：

1。邮件交换器记录（MX记录）指定负责代表域名接受电子邮件的邮件服务器。上面提到的文档页面是关于使用G Suite 发送电子邮件的。

1. A mail exchanger record (MX record) specifies the mail server responsible for accepting email messages on behalf of a domain name. The mentioned doc page is about using G Suite to send email.

2。请参阅1，那些是接收发往gmail的电子邮件的Google服务器。

2. See 1, Those are Google servers which receive email destined to gmail.

3。和4.有时（甚至可能非常频繁），同一台服务器既负责发送电子邮件，也负责接收域的电子邮件。电子邮件提供商越大，我猜这些角色被分开的机会就越大。因此，其他域的电子邮件服务器将使用MX查找返回的服务器向 gmail发送电子邮件，但是其中一个（作为gmail用户）不能使用它们向其他域发送电子邮件。

3. and 4. Sometimes (or maybe even very often), the same server(s) are responsible both for both sending emails out, and receiving emails for the domain. The bigger the email provider, I guess the bigger the chance that those roles are separated. So, other domain's email servers will use servers returned by MX lookup to send emails to gmail, but one (as gmail user) can't use them to send emails to other domains.

5。对于是部分，不需要身份验证（您无需任何gmail凭据即可向@gmail用户发送电子邮件）

5. For the "yes" part, no authentication is needed (you don't need any gmail credentials in order to send email to @gmail user)

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