How the mail flow occur in exchange server 2013

In Exchange Server 2013, the mail flow process involves several components and steps. Here's an overview of the process:

Step 1: Incoming Mail

• An external sender sends an email to a recipient's email address.
• The email is received by the Edge Transport server (if configured) or the Hub Transport server.
• The Edge Transport server is responsible for receiving and filtering incoming mail from the internet.

Step 2: Authentication

• The incoming email is authenticated using various methods, such as:
  • DNS-based Authentication of Named Entities (DANE)
  • DomainKeys Identified Mail (DKIM)
  • Sender Policy Framework (SPF)
  • Transport Layer Security (TLS)
• The authentication process verifies the sender's identity and ensures that the email is not spoofed.

Step 3: Filtering

• The incoming email is filtered using various filters, such as:
  • Anti-spam filters (e.g., SpamAssassin)
  • Anti-malware filters (e.g., Microsoft Forefront Online Protection for Exchange)
  • Content filters (e.g., Exchange Server's built-in content filters)
• The filters scan the email for spam, viruses, and other malicious content.

Step 4: Routing

• The filtered email is routed to the Hub Transport server.
• The Hub Transport server is responsible for routing the email to the recipient's mailbox.
• The routing process involves checking the recipient's email address, mailbox location, and other factors to determine the best route for the email.

Step 5: Delivery

• The email is delivered to the recipient's mailbox on the Mailbox server.
• The Mailbox server is responsible for storing and managing the recipient's email messages.

Step 6: Pickup

• The email is picked up by the Mailbox server's pickup service.
• The pickup service is responsible for retrieving emails from the mailbox and making them available for the recipient to read.

Step 7: Read

• The recipient reads the email using their email client (e.g., Outlook, Outlook Web App, or a mobile device).
• The email client connects to the Mailbox server to retrieve the email.

Additional Components

• Transport Agents: These are custom scripts that can be used to perform additional processing on incoming and outgoing emails, such as encryption, decryption, and content filtering.
• Mail Flow Rules: These are custom rules that can be used to route emails based on specific conditions, such as sender, recipient, or content.

In summary, the mail flow process in Exchange Server 2013 involves authentication, filtering, routing, delivery, pickup, and read. The process involves several components, including Edge Transport servers, Hub Transport servers, Mailbox servers, and transport agents.