Editing Email (section)

==Servers and client applications==
[[File: Mozilla Thunderbird 3.1.png|thumb|The interface of an [[email client]], [[Mozilla Thunderbird|Thunderbird]]]]
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Messages are exchanged between hosts using the [[Simple Mail Transfer Protocol]] with software programs called [[mail transfer agent]]s (MTAs); and delivered to a mail store by programs called [[mail delivery agent]]s (MDAs, also sometimes called local delivery agents, LDAs). Accepting a message obliges an MTA to deliver it,<ref>In practice, some accepted messages may nowadays not be delivered to the recipient's InBox, but instead to a Spam or Junk folder which, especially in a corporate environment, may be inaccessible to the recipient</ref> and when a message cannot be delivered, that MTA must send a [[bounce message]] back to the sender, indicating the problem.

Users can retrieve their messages from servers using standard protocols such as [[Post Office Protocol|POP]] or [[IMAP]], or, as is more likely in a large [[corporation|corporate]] environment, with a [[Proprietary software|proprietary]] protocol specific to [[Novell Groupwise]], [[Lotus Notes]] or [[Microsoft Exchange Server]]s.  Programs used by users for retrieving, reading, and managing email are called [[mail user agent]]s (MUAs).

When opening an email, it is marked as "read", which typically visibly distinguishes it from "unread" messages on clients' user interfaces. Email clients may allow hiding read emails from the inbox so the user can focus on the unread.<ref>{{cite web |title=View only unread messages |url=https://support.microsoft.com/en-us/office/view-only-unread-messages-f2c8450c-9cd0-4037-a5d3-26f6946727ca |website=support.microsoft.com |access-date=November 13, 2021 |archive-date=November 13, 2021 |archive-url=https://web.archive.org/web/20211113164358/https://support.microsoft.com/en-us/office/view-only-unread-messages-f2c8450c-9cd0-4037-a5d3-26f6946727ca |url-status=live }}</ref>

Mail can be stored on the [[client (computing)|client]], on the [[Server (computing)|server]] side, or in both places. Standard formats for mailboxes include [[Maildir]] and [[mbox]]. Several prominent email clients use their own proprietary format and require conversion software to transfer email between them. Server-side storage is often in a proprietary format but since access is through a standard protocol such as IMAP, moving email from one server to another can be done with any [[Mail user agent|MUA]] supporting the protocol.

Many current email users do not run MTA, MDA or MUA programs themselves, but use a web-based email platform, such as [[Gmail]] or [[Yahoo! Mail]], that performs the same tasks.<ref>{{Cite web|url=https://dir.yahoo.com/business_and_economy/business_to_business/communications_and_networking/internet_and_world_wide_web/email_providers/free_email/|title=Free Email Providers in the Yahoo! Directory|website=dir.yahoo.com|archive-url=https://web.archive.org/web/20140704154604/https://dir.yahoo.com/business_and_economy/business_to_business/communications_and_networking/internet_and_world_wide_web/email_providers/free_email/|archive-date=2014-07-04|url-status=dead}}</ref> Such [[webmail]] interfaces allow users to access their mail with any standard [[web browser]], from any computer, rather than relying on a local email client.

===Filename extensions===
Upon reception of email messages, email client applications save messages in operating system files in the file system. Some clients save individual messages as separate files, while others use various database formats, often proprietary, for collective storage. A historical standard of storage is the ''mbox'' format. The specific format used is often indicated by special [[filename extension]]s:
;<code>eml</code>
:Used by many email clients including [[Novell GroupWise]], [[Microsoft Outlook Express]], [[Lotus notes]], [[Windows Mail]], [[Mozilla Thunderbird]], and Postbox. The files contain the email contents as [[plain text]] in [[MIME]] format, containing the email header and body, including attachments in one or more of several formats.
;<code>emlx</code>
:Used by [[Apple Mail]].
;<code>msg</code>
:Used by [[Microsoft Outlook|Microsoft Office Outlook]] and [[OfficeLogic|OfficeLogic Groupware]].
;<code>mbx</code>
:Used by Opera Mail, [[KMail]], and [[Apple Mail]] based on the mbox format.

Some applications (like [[Apple Mail]]) leave attachments encoded in messages for searching while also saving separate copies of the attachments. Others separate attachments from messages and save them in a specific directory.

===URI scheme mailto===
{{main|mailto}}
The [[URI scheme]], as registered with the IANA, defines the <code>mailto:</code> scheme for SMTP email addresses. Though its use is not strictly defined, URLs of this form are intended to be used to open the new message window of the user's mail client when the URL is activated, with the address as defined by the URL in the ''To:'' field.<ref>RFC 2368 section 3 : by Paul Hoffman in 1998 discusses operation of the "mailto" URL.</ref><ref name="Barnett 2011 p. 245" /> Many clients also support query string parameters for the other email fields, such as its subject line or carbon copy recipients.<ref>{{Cite web|url=https://developer.mozilla.org/en-US/docs/Learn/HTML/Introduction_to_HTML/Creating_hyperlinks|title=Creating hyperlinks § E-mail links|website=MDN Web Docs|language=en|access-date=2019-09-30|archive-date=August 18, 2019|archive-url=https://web.archive.org/web/20190818224233/https://developer.mozilla.org/en-US/docs/Learn/HTML/Introduction_to_HTML/Creating_hyperlinks|url-status=live}}</ref>