Email Architecture and How It Works : Same Domain and Different Domain
Email Architecture and How It Works :
Same Domain and Different Domain
Electronic mail has three parts: envelope, header, and body of email. Envelope determines where the email will be sent, or if it can not be delivered, where the email will be returned.
Header is a property pair and its value corresponds to RFC2822. Headers can contain various information about emails along the way from the start of emails processed by the sending server or MUA to the receiving server such as the date, MUA used, and the server being traversed.
Headers may contain information that is specific to a particular application that may be useful for the application but will be ignored by email system. The information begins with "x-". While the body of the email is the content of the email itself. Email body in the form plain text, although sometimes the plain text is the result of encryption.
Header is one of the important sources of information in email. If there is a problem with the email system, the information in that header will be great
particularly useful for analyzing problems occurred.
For that, as an admin it's a good idea to start getting used to seeing the full header of emails that are normally hidden by the MUA from view. We try to see the complete header of the email and dissect it. The following information is the information contained in the email headers.
The first line in the header is a line added by mail.local or a local sending agent. The next few lines of the line that begin with x- are lines added by MUA in this case are the Mozzila Thunderbird client app.
Return-Path informs the SMTP server that email will be returned in case of an error such as a local destination address not found.
Return-Path can contain an address different from the Form header
How Same Domain Works ?
This section records each server the email passes during its journey from the sender to the recipient. Each skipped server will add a new received line, so there are many lines of received: when email passes a long route.
This line will store information about the name of the sender server, the name of the recipient server, the server application used, the email id on the receiving server, the date, and the time. The bottom Received line represents the source server information or the sender's MUA and the top line is the receiving server.
If noticed, the email is from icx@webmail.bppt.go.id and addressed to icx@biopotek.bppt.go.id. If searched from below, or from the sender, the email is received by a bppt.go.id server running the CommuniGate Pro WebUser version 3.54 application with ID 4239723 from IP address 180.214.233.7
The email is received by server.bppt.go.id at 20:44:18. It is possible emails are sent via the web interface. The email is then received by the serverMailx.biopotek.bppt.go.id that runs the Postfix application with queue ID 596285D37FD at 20:44:21.But the email is then received by the local host from the mailx.biopotek.go.id server with the email ID 0dGR09 + cTfNo at the same time 20:44:21. Or in other words the email is forwarded to the same machine.
For what is email forwarded to the same machine, not to the recipient's mailbox? When viewed again, note that the email is likely to be forwardedTo amavisd-new to scan whether the email contains virus or not, and this is explained in the line above it is x-Virus-Scanned: amavisd-new at biopotek.bppt.go.id.But then the email is received back by the local host.The recipient of the email by the local host twice as amavisd-new does not perform the scan, but other applications do so. Amavisd-new submits an emailTo the application and then amavisd-new receives back an email that has been scanned so that 2 local hosted emails receive mail.
Lastly, the email is finally received by the mail.biopotek.go.id host that runs Postfix with queue ID 99040465A2 at 20:44:26.Visible emails move from mail.bipotek.bppt.go.id to mail.biopotek.bppt.go.id.Host mail.biopotek.go.id is the final destination and host mailx.biopotek.go.id seems to be a host that acts as an SMTP gateway or domain biopotek.bppt.go.idHave split DNS and host mailx.biopotek.bppt.go.id is MX which is visible from outside so email through MX.
The next few lines are standard lines added by the system or MUA as well as x-Mailers that seem to be added by the SMTP server application used by the sender. From: and To: are the email address and email destination.
Subject: is the title of the email added by the sending client. Date: is the date and time of sending the email. MIME-Version: and Content-Type are the version of MIME used and the body type of email.
If the email has an attachment, then the MIME type is multipart / mixed. Message-IDL is a unique ID that is added by the system that sends the email when
the email is received by the sending system. This ID is different from the queue ID.
How Different Domains Works ?
To be able to send email from different domains then email must be sent via SMTP relay server. A server relay is a link that receives mail from the client and sends it to the SMTP server from the intended sender. This SMTP server is called the MX server (Main eXchange). To find out which MX server is redeeming mail for a particular domain, the server relay will query the domain to the DNS MX loop.
- The client hands over the email via the SMTP protocol to its SMTP relay server
- The SMTP relay server checks each recipient's email address, then retrieves the domain on each address and asks it for DNS Server, "Oy, DNS, MX Which server with this domain ?"
- After the SMTP relay gets replies, SMTP relay creates an SMTP connection with the MX server for all receiving domains and submits email message data.
- Each MX receiver server stores messages to the user's mail box
In fact, the above process may involve some DNS servers for better performance (and the recipient domain may also use MX Server) but the working principle is still the same.
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