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The SMTP Servers – What SMTP Is And How It Works

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Godwin here. Why am I writing this? When I was thinking about a way to host and take control of my email marketing and autoresponder system, there weren’t any much information out there to guide me. Hence, I am writing this to offer assistance to anyone who find themselve in same position I was. Possibly you’re one of them. If yes, then you’re in the right place.

But be warned, I’ll be going into complex technical operation of Simple Mail Transfer Protocol, so if that’s something you might not want to read, then you may as well leave now. But if you’re still here, then read with undivided attention so as to have a better understanding. This is important because, with SMTP you can avoid the high cost of autoresponder services and still execute your email marketing.

Send Emails Without Autoresponder

The solution for sending emails without an auto-responder is using SMTP.I will be giving you anoverview of how it works. If you’re ready, lets go!Whenever you send a piece of email,your e-mail client (e.g. Eudora, Thunderbird, Outlook, etc.) interacts with the SMTP server on a webhost to handle the sending. The SMTP server on yourhost may have conversations with other SMTP servers to deliver the e-mail.

You will be able to send MILLIONS OF EMAILS every single day, without breaking a sweat and not worry about GetResponse or Aweber Bans

With Your Self Hosted Email Servers you will be able to upload lists without verification, delete subscribers, choose your sender name & email addresses and there are NO BANS!


If your database is bad, your server IPs are going to be blacklisted = NO INBOXING!

If you’re just spamming, the way I teach you in this blog post is not going to work =DON’T SPAM!

It’s a little expensive than subscriber based systems like Aweber & GetResponse. With Self hosted you pay per email. But if you’re doing it right, you’re going to make more than enough to cover the bills and make a healthy profit.

If you use Amazon SES it will be cheaper because there rates per email are downright ridiculous. With other SMTPs, the rates vary.

SMTP Services Recommended:

1. Amazon SES  – Note: Avoid sending make money online offers with SES.

2. Mandrill – Super cheap to send out emails, but make sure your data is squeaky clean & always include unsubscribe link.

3. SendGrid – Great delivery rates but a little expensive if you want to send out millions of emails per month. But if you’re sending highly relevant information only a few times per month this is one of the best services on the planet.

I own and use all these services myself and I don’t recommend anything that I don’t personally use on this blog.

Server Features

First, a quick overview of the features we’ll be getting from our modern email server:

  • Email storage is encrypted on the server.
  • Full encryption over the wire with TLS.
  • Server is locked-on-boot, SSH on reboots to unlock.
  • Better SPAM detection.
  • Lightning fast push support on all devices.
  • Full-text search that actually works.
  • Server software and all packages are open source.

Furthermore, our email server is built from a number of separate little projects that work together, including:

Postfix – the Mail Transfer Agent (MTA) that handles relaying mail between different servers. It decides what to do with email from the outside world, and whether a particular user is allowed to send email using the server. Postfix hands off local delivery (that is, the actual saving of the mail files on the server) to Dovecot. Postfix also lets Dovecot take care of authentication before users are allowed to send email from the server.

Dovecot – the Local Mail Transfer Protocol service (LMTP), in email lingo, it essentially runs IMAP to handle requests from users who want to authenticate and check their email. Dovecot’s LMTP service functions as the Mail Delivery Agent (MDA) by saving mail files on the server. Dovecot also handles all authorization. It checks users’ email addresses and passwords in the MySQL database before allowing them to view or send email.

EncFS – this is used to encrypt our email store.

OpenDKIM – DKIM digitally signs all messages on the server to verify the message actually was sent from the domain in question and is not spam or phishing.

MySQL – the database server stores lookup tables for domains, usernames and passwords, and aliases on the mail server.

Protips and caveats

Congratulations for making to the end. I’m sure your brain must have had some exercise in trying to comprehend the ways of the Email as illustrated in the foregoing explanation. Go ahead and use your knowledge in hosting your own email campaigns.

For assistance to host your own email marketing campaign contact us

For a complete down to earth guide on how you can successfully self host your own independent autoresponder click here

If you have been educated by the informatione contained in this write, do well to encourage us here by posting your opinion or questions or comments below. Thanks in anticipation.

SMTP – How It Works

I would like to explain with a typical illustration. Let’s assume that I want tosend a piece of e-mail. My e-mail ID is godwin, and I have my account on aogodwin.com. I want to send e-mail to peacealeru@yahoo.com. I am using a stand-alone e-mail client like Outlook Express.

When I set up my email account at aogodwin.com, I told Outlook Express the name of the mail server — mail.aogodwin.com.com. When I compose a message and press the Send button, here’swhat happens:

1. Outlook Express connects to the SMTP server at mail.aogodwin.com.com using port 25.

2. Outlook Express has a conversation with the SMTP server, telling the SMTP server the address ofthe sender and the address of the recipient, as well as the body of the message.

3. The SMTP server takes the “to” address (peacealeru@yahoo.com) and breaks it into two parts: the recipient name (peacealeru) and the domain name (yahoo.com). If the “to” address had been another user at aogodwin.com.com, the SMTP server would simply hand the message to the POP3 server for aogodwin.com.com (using a little program called the delivery agent). Sincethe recipient is at another domain, SMTP needs to communicate with that domain.

4. The SMTP server has a conversation with a Domain Name Server, or DNS It says, “Can you giveme the IP address of the SMTP server for yahoo.com?” The DNS replies with the one or more IPaddresses for the SMTP server(s) that Yahoo operates.

5. The SMTP server at aogodwin.com.com connects with the SMTP server at Yahoo using port25. It has the same simple text conversation that my e-mail client had with the SMTP server for aogodwin.com, and gives the message to the Yahoo server. The Yahoo server recognizes that the domain name for peacealeru is at Yahoo, so it hands the message to Yahoo’s POP3 server, which puts the message in peacealeru’s mailbox.

If, for some reason, the SMTP server at aogodwin.com cannot connect with the SMTP server atYahoo, then the message goes into a queue. The SMTP server on most machines uses a program calledsendmail to do the actual sending, so this queue is called the sendmail queue. Sendmail will periodicallytry to resend the messages in its queue.

For example, it might retry every 15 minutes. After four hours,it will usually send you a piece of mail that tells you there is some sort of problem. After five days, mostsendmail configurations give up and return the mail to you undelivered.

The SMTP server understands very simple text commands like HELO, MAIL, RCPT and DATA. The mostcommon commands are:

HELO – introduce yourself

EHLO – introduce yourself and request extended mode

MAIL FROM: – specify the sender

RCPT TO: – specify the recipient

DATA – specify the body of the message (To, From and Subject should be the first three lines.)

RSET – reset

QUIT – quit the session

HELP – get help on commands

VRFY – verify an address

EXPN – expand an address

VERB – verbose

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Here’s a summarized overview of how SMTP works:

  1. Client-Server Communication: When you compose an email and click “send” in your email client (such as Gmail or Outlook), the client software communicates with an SMTP server. This server is typically provided by your email service provider or your organization.
  2. Establishing Connection: The client initiates a connection with the SMTP server on a specific port (usually port 25). This connection is typically established using the TCP/IP network protocol.
  3. Handshaking: Once the connection is established, the client and server perform a handshake process to verify each other’s identity and negotiate the details of the email transfer. This includes exchanging information about the supported authentication methods, encryption options, and the sender and recipient email addresses.
  4. Email Transfer: After the handshake, the client submits the email message to the SMTP server for delivery. This includes specifying the recipient’s email address, subject, message body, and any attachments.
  5. Email Routing: The SMTP server analyzes the recipient’s email address and determines the appropriate destination server for the email. It does this by looking up the domain name (the part after the ‘@’ symbol) in the DNS (Domain Name System) to find the MX (Mail Exchange) records that identify the mail server responsible for that domain.
  6. Relaying: If the recipient’s email address domain is different from the sender’s domain, the SMTP server may need to relay the email to other servers to reach the final destination. This involves establishing connections with other SMTP servers in a chain until the email reaches the recipient’s mail server.
  7. Delivery or Storage: Once the email reaches the recipient’s mail server, that server stores the email in the recipient’s mailbox or forwards it to another email client for retrieval by the recipient.

SMTP is a store-and-forward protocol, which means that if the recipient’s mail server is temporarily unavailable, the sending server will try again later until the message is successfully delivered or until it reaches a maximum retry limit.

It’s worth noting that SMTP is primarily used for sending emails, while other protocols like POP3 (Post Office Protocol version 3) or IMAP (Internet Message Access Protocol) are used for retrieving emails from mail servers.

Overall, SMTP servers play a crucial role in facilitating the transfer of email messages across different email systems and networks.

If you have enjoyed this article, help someone get to know these things by sharing it with your friends and followers on social media.

Also don’t hesitate to tell us your opinion or suggestion or recommendation on the comment box below, doing so will encourage us to do more as well as further educate others about your view point, Thanks in anticipation.

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