A protocol used to access a mailbox and download e mail

You're referring to a protocol used to access a mailbox and download email!

There are several protocols used to access email, but some of the most common ones are:

1. POP3 (Post Office Protocol version 3): POP3 is a widely used protocol for retrieving email from a mail server. When you use POP3, your email client downloads the email from the server and stores it on your local device. The email is then deleted from the server, unless you configure your client to leave a copy on the server.
2. IMAP (Internet Message Access Protocol): IMAP is another popular protocol for accessing email. Unlike POP3, IMAP allows you to access your email from multiple devices and keeps a copy of the email on the server. This means you can access your email from anywhere and see the same messages, without having to download them to your local device.
3. SMTP (Simple Mail Transfer Protocol): SMTP is a protocol used for sending email. It's not typically used for accessing email, but rather for sending emails from your email client to a mail server.
4. Exchange ActiveSync (EAS): EAS is a protocol used for accessing email, contacts, and calendar information on Microsoft Exchange servers. It's commonly used for mobile devices and allows for two-way synchronization of data between the device and the server.

These protocols are used by email clients, such as Microsoft Outlook, Mozilla Thunderbird, and Apple Mail, to access and manage email accounts.