In the process of sending an email, you're dealing with (among other things) email servers and email clients. Often used interchangeably, the two systems are very different. In general, a mail server is a backend system that manages email messages. In contrast, a mail client is a frontend program that allows users to access and interact with those messages.
A mail server is a computer system that manages and sends email messages. It stores email messages on behalf of one or more clients, and provides services to allow clients to send and receive email messages.
There are several types of mail servers, including SMTP (Simple Mail Transfer Protocol) servers, which are used to send email messages, and IMAP (Internet Message Access Protocol) and POP (Post Office Protocol) servers, which are used to receive email messages.
A mail client, on the other hand, is a software program that is used to access and manage email messages on a mail server. Mail clients allow users to send and receive email messages, as well as to store and organize their email messages.
Examples of mail clients include Microsoft Outlook, Apple Mail, and Gmail. These programs can be used to connect to a mail server, retrieve email messages, and send email messages to other users.