Exchange Mail Flow and Recipient Types

Contents:

Exchange Mail Flow Design and Configuration

SMTP & DNS protocol in Mail Flow Conceptual Aspect

Simple Mail Transfer Protocol (RFC5321)

SMTP (RFC5321) Explanation

[!INFO]
SMTP Service Extension for Secure SMTP over Transport Layer Security (RFC3207) ~ STARTTLS command for secure SMTP

EHLO movetocloud.online
MAIL FROM: mimi@movetocloud.online
RCPT TO: kjpark@tdgl.co.kr
DATA
Subject: Test mail flow to tdgl.co.kr

This is a test message...
.

SMTP Command

[!INFO]
Use Telnet to test SMTP communication on Exchange servers

Domain Names

DNS Structure

DNS Query

Exchange Mail Flow & Client Access for DNS Resource Records

MX Record

Recipient Domain의 Mail Exchanger의 정보를 나타냄.

MX Record Explanation

Sender Policy Framework (SPF: RFC4408)

Mail의 Sender(Mail Exchanger)를 확인하는 과정을 통해 phishing 이나 spam을 줄이기 위하여 사용되어지는 기술.

Sender domain 공인된 DNS의 다음 record들 Query하여 Sender ID를 확인:

[!INFO]
SPF Record Syntax (open-spf.org)

DKIM (RFC5585) & DMARC (RFC7489)
AUTODISCOVER.TDGL.CO.KR (A | CNAME | SRV Record)

Inbound & Outbound Mail Flow

Inbound Mail Flow

Inbound Mail Flow without Edge

Inbound Mail Flow without Edge

Inbound Mail Flow with Edge

Inbound Mail Flow with Edge

Outbound Mail Flow

Outbound Mail Flow without Edge

Outbound Mail Flow without Edge

Outbound Mail Flow with Edge

Outbound Mail Flow with Edge

Non-delivery Reports

Connectors & Accepted Domains

Exchange Connectors
Accepted Domain

Accepted Domains은 Exchange Organization의 메일을 수신하게 구성된 SMTP address namespace. Email Address Policies에서 사용.

Transport Availability and Features

Transport Agents

Transport Agent는 Microsoft 또는 3rd-Party vendor에 제공하는 소프트웨어를 설치할 수 있으며, transport pipeline을 통해 들어온 email messages들에 대한 추가적인 process 또는 action 처리를 할 수 있게 합니다.

Transport Agent 분류

[!INFO]
Built-in Transport Agent | Microsoft Docs

Mail Flow & Transport Pipeline | Microsoft Docs

Transport Pipeline Overview

Transport High Availability & Queues

Transport High Availability

Exchange 서버는 message가 성공적으로 배달되기 전/후로 redundant copies를 유지하여 Transport에 대한 High Availability를 확보합니다.

Exchange 서버의 Transport High Availability을 제공하는 핵심 기능은 아래와 같습니다:

Transport High Availablity with Shadow Redundancy and Safety Net

Exchange Transport High Availability

Queues and messages in queues in Exchange Server | Microsoft Docs

Message Size and Recipient Limits

Scope of Limits

  1. Organizational Limits
  2. Connector Limits
  3. Server Limits
  4. Recipient Limits

Types of message size limits

Exchange Recipient Types and Explanation

Exchange Recipient Types

Mailbox

Distribution Groups

Exchange에서 사용하는 대표적인 group objects들은 아래와 같습니다:

Exchange Organization의 외부에 존재하는 사용들에 대한 정보를 포함.

Recipient Features

Messaging policy and compliance

https://learn.microsoft.com/en-us/exchange/policy-and-compliance/policy-and-compliance

Feature Description
In-Place Archiving In-Place Archiving helps you regain control of your organization’s messaging data by eliminating the need for personal store (.pst) files and allowing users to store messages in an archive mailbox accessible in Outlook 2010 and later and Outlook on the web.
In-Place Hold and Litigation Hold When a reasonable expectation of litigation exists, organizations are required to preserve electronically stored information, including email that’s relevant to the case. In-Place Hold allows you to search and preserve messages matching query parameters. Litigation Hold only allows you to place all items in a mailbox on hold. For both types of holds, messages are protected from permanent deletion, modification, and tampering and can be preserved indefinitely or for a specified period.
In-Place eDiscovery In-Place eDiscovery allows you to search mailbox data across your Exchange organization, preview search results, copy search results to a Discovery mailbox, or export the results to a PST file
Administrator audit logging Administrator audit logs enable you to keep a log of changes made by administrators to Exchange server and organization configuration and to Exchange recipients. You might use administrator audit logging as part of your change control process or to track changes and access to configuration and recipients for compliance purposes.
Mailbox audit logging Because mailboxes can potentially contain sensitive, high business impact information and personally identifiable information, it’s important that you track who logs on to the mailboxes in your organization and what actions are taken. It’s especially important to track access to mailboxes by users other than the mailbox owner (known as delegate users). Using mailbox audit logging, you can log mailbox access by administrators, delegates (including administrators with full access permissions), and mailbox owners.
Data loss prevention Data loss prevention (DLP) in Exchange Server includes 80 sensitive information types that are ready for you to use in your DLP policies.
Mail flow rules (also known as transport rules) Use mail flow rules to look for specific conditions in messages that pass through your organization and take action on them. You can use conditions and exceptions to define when a mail flow rule is applied, and then apply an action on messages when the conditions are met.

Mailbox Permissions & Search, Move

Exchange Clients Services

Clients Type & Services

Autodiscover Service

MAPI over HTTP & POP3, IMAP

Mobile Outlook App & ActiveSync

Outlook on the Web

Mailbox Access & Policies

Mailbox Access

Mobile Device Mailbox Policy

OWA Mailbox Policy