What protocol is used between Email servers?

The protocol that is used between Email servers is SMTP (Simple Mail Transfer Protocol). This protocol is specifically designed to send and receive email messages over the internet.
SMTP enables the communication between the email client and the mail server, as well as between the mail servers themselves. When you want to send an email, your email client uses SMTP to communicate with your email server and submits the email message for delivery.
SMTP works in a simple, yet effective way. When you hit the "Send" button on your email client, it initiates a connection to your email server using TCP/IP (Transmission Control Protocol/Internet Protocol). The email client then sends the email message along with the recipient's email address to the server.
The server receiving the email checks the recipient's domain name (the part after the @ symbol) to determine the appropriate destination server. It then connects to the destination server using SMTP and sends the email message to that server.
Once the destination server receives the email, it stores it in the recipient's mailbox until it is retrieved by the recipient's email client. This retrieval is typically done using other protocols such as POP (Post Office Protocol) or IMAP (Internet Message Access Protocol).
In summary, SMTP is the protocol responsible for the transmission of email messages between different mail servers. It ensures that the emails are delivered to the correct destination server, allowing for efficient communication across the internet.