Have you had experience working with the POP3 protocol for receiving emails?

Yes, I have experience working with the POP3 protocol for receiving emails. POP3 (Post Office Protocol version 3) is a simple protocol that allows a client to download emails from a mail server and usually delete them from the server after downloading.

In Go, you can use third-party libraries to work with POP3, such as github.com/bytbox/go-pop3. The main steps are:

1. Establish a connection to the POP3 server.
2. Authenticate using a login and password.
3. Retrieve the list of emails.
4. Download the necessary emails.
5. Close the connection.

Example of using the library:

package main

import (
    "fmt"
    "log"
    "github.com/bytbox/go-pop3"
)

func main() {
    client, err := pop3.Dial("pop.mailserver.com:110")
    if err != nil {
        log.Fatal(err)
    }
    defer client.Quit()

    if err := client.Auth("username", "password"); err != nil {
        log.Fatal(err)
    }

    count, _, err := client.Stat()
    if err != nil {
        log.Fatal(err)
    }

    for i := 1; i <= count; i++ {
        msg, err := client.Retr(i)
        if err != nil {
            log.Println("Error retrieving message", i, err)
            continue
        }
        fmt.Printf("Message %d:\n%s\n", i, string(msg))
    }
}

This example demonstrates basic POP3 operations in Go.