What happens behind the scenes when you send an email, before it reaches its destination?

Q. What happens behind the scenes when you send an email, before it reaches its destination?

Answer =

(i) You compose and send an email from your email client. Your email has the recipient's email address along the email message.

(ii) Now your email client connects to the Outgoing SMTP server and hands over the email message in the required format.

(iii) The Outgoing SMTP first validates the sender details and if valid processes the message for sending and places it in Outgoing queue.

(iv) Next DNS look up takes place. The SMTP server based on the domain details in the recipient address, looks up the DNS server of the domain and retrieves the Recipient server information (such as MX records) of the recipient domain.

Mail Exchange (MX) records are DNS records that are necessary for delivering email to the recipient's address.

(v) Then the SMTP server connects with the Recipient email server and sends the email through SMTP protocol.

(vi) The Recipient server in turn validates the recipient account and delivers the email to the users mail account.

(vii) The user logs into own email account and views the received email using email client that will use POP3/IMAP protocols.

For example:-

You have sent an email from your email account abc@gmail.com to xyz@edup.com. Once you click send button :

(a) Your email client contacts SMTP server of Gmail (since your email account is on gmail.com)

(b) The SMTP server at Gmail checks your email for recipient's email address and the recipient's address xyz@edup.com is extracted.

(c) Next, the Gmail SMTP server looks for the MX (mail exchange) record of edup.com from DNS.

(d) Now the GMAIL's SMTP server will retrieve the address of SMTP server of edup.com from its MX record and sends the email to SMTP server of edup.com.

(e) The SMTP server of edup.com receives the email message.

(f) The SMTP server of edup.com checks if the 'xyz' recipient exists on that server (edup.com). If the account exists on that server, it forwards the email to its own IMAP/POP3 server (mail delivery agent) to store this email.