Email - how it works
From JumbaWiki
- For more information, see main article: Email
Email messages are sent between computers using the Simple Mail Transfer Protocol (SMTP), by software called mail transport agents (MTA). Mail transport agents are also known as mail servers, or mail exchangers. When a message cannot be delivered, the recipient MTA sends a bounce message back to the sender, indicating the problem.
Users can download their messages from servers with standard protocols such as the POP or IMAP protocols, or with a proprietary protocol specific to Lotus Notes or Microsoft Exchange Servers.
Internal format
Internet email messages consist of two major sections:
- Header -- Structured into fields such as summary, sender, receiver, and other information about the email
- Body -- The message itself as unstructured text; sometimes containing a signature block at the end
The header is separated from the body by a blank line.
Email can also be multi-part using MIME (Multipurpose Internet Mail Extensions). This allows email to contain an HTML formatted body, and also contain a text-only version of the body for email clients that don't understand HTML. Non-text email attachments can also be included in multi-part emails, for example image or video files.
