Apple Mail
Apple Mail (officially known as simply Mail) is an email client included by Apple Inc. with its operating systems macOS, iOS, iPadOS and watchOS. Apple Mail grew out of NeXTMail, which was originally developed by NeXT as part of its NeXTSTEP operating system, after Apple's acquisition of NeXT in 1997.

The current version of Apple Mail utilizes SMTP for message sending, POP3, Exchange and IMAP for message retrieval and S/MIME for end-to-end message encryption. It is also preconfigured to work with popular email providers, such as Yahoo! Mail, AOL Mail, Gmail, Outlook and iCloud (formerly MobileMe) and it supports Exchange. iOS features a mobile version of Apple Mail with added Exchange ActiveSync (EAS) support, though it notoriously missed the functionality of attaching files to reply emails until the release of iOS 9. EAS is not supported in the macOS version of Apple's Mail app, the main issue being that sent messages will incorrectly be duplicated in the sent messages folder, which then propagates via sync to all other devices including iOS.

Features of Apple Mail include the ability to configure the software to receive all of a user's email accounts in the one list, ability to file emails into folders, ability to search for emails, and ability to automatically append signatures to outgoing emails. It also integrates with the Contacts list, Calendar, Maps and other apps.

History

NeXTMail
Apple Mail was originally developed by NeXT as NeXTMail, the email application for its NeXTSTEP operating system. It supported rich text formatting with images and voice messaging, and MIME emails. It also supported a text-based user interface (TUI) to allow for backwards compatibility. 

When Apple began to adapt NeXTSTEP to become Mac OS X, both the operating system and the application went through various stages as it was developed. In a beta version (codenamed "Rhapsody") and various other early pre-releases of Mac OS X, Mail was known as MailViewer. However, with the third developer release of Mac OS X, the application had returned to being known simply as Mail.

First release
Apple Mail was included in all versions of macOS up to and including Mac OS X Panther, which was released on October 24, 2003. It was integrated with other Apple applications such as Address Book, iChat, and iCal. Some of its features that remain in the most recent version of Mail include rules for mailboxes, junk mail filtering and multiple account management.

Mac OS X Tiger
In Mac OS X Tiger (version 10.4), Mail version 2 included a proprietary single-message-per-file format (with the filename extension .emlx) to permit indexing by Spotlight. Additional features were:
 "Smart mailboxes" that used Spotlight technology to sort mail into folders.
 the ability to flag messages with a low, normal or high priority and to use these priorities in mailbox rules and smart mailboxes.
 tools for resizing photos before they are sent to avoid oversized email attachments.
 the ability to view emailed pictures as a full-screen slideshow.
 parental controls to specify who is allowed to send email to children.
 HTML message composition.

The new version also changed the UI for the buttons in the toolbar. Whereas previous buttons had free-standing defined shapes, the new buttons featured shapes within a lozenge-shaped capsule. According to many users, and even Apple's own human interface guidelines at the time, this was worse for usability. An open-source third-party application that reverted the icons to their former shapes was available. Nevertheless, Apple updated their guidelines to include capsule-shaped buttons, and the new UI persisted.

Mac OS X Leopard
In Mac OS X Leopard (version 10.5), Mail version 3 included personalized stationery, handled in standard HTML format. In addition, it offered notes and to-dos (which could be synced with iCal) as well as a built-in RSS reader. It also introduced IMAP IDLE support for account inboxes.

Mac OS X Snow Leopard
Mac OS X Snow Leopard (version 10.6) brought Microsoft Exchange Server 2007 support.

Mac OS X Lion
In Mac OS X Lion (version 10.7), Mail featured a redesigned iPad-like user interface with full-screen capabilities, an updated message search interface, support for Microsoft Exchange Server 2010 and Yahoo! Mail (via IMAP). Also added was the capability to group messages by subject in a similar fashion to Mail on iOS 4. The bounce function, where unwanted emails could be bounced back to the sender, was dropped, as was support for Exchange push email.

OS X Mountain Lion
In OS X Mountain Lion (version 10.8), Mail received VIP tagging, Safari-style inline search for words within an email message, the ability to sync with iCloud and new sharing features. Notes was split off into a stand-alone application. The RSS reader and to-dos were discontinued.

OS X Mavericks
In OS X Mavericks (version 10.9), Mail ceased support for plain-text MIME multipart/alternative messages and solely retained the HTML or rich-text version.

OS X Yosemite
In OS X Yosemite (version 10.10), Mail introduced Markup (inline annotation of PDF or image files) and Mail Drop (automatically uploads attachments to iCloud, and sends a link in the message instead of the whole file).

OS X El Capitan
In OS X El Capitan (version 10.11), a filter was added to the message list to filter by various options such as Unread, Flagged, or messages with attachments. The conversation display was also redesigned and various disk space saving optimizations were implemented. Streaming notification support for Exchange accounts was also added.

macOS High Sierra 
In macOS 11.13 (High Sierra) Mail reached version 11.5, a version that was not further upgraded (in High Sierra, at least until 2021).

macOS Mojave
Support for macOS's new "dark mode" was added to Mail.

macOS Catalina
Added support for Block Sender, Unsubscribe, Mute Thread and layout options.

macOS Big Sur
In macOS Big Sur, the Mail logo was changed to be more consistent with the iOS version, depicting a white envelope on a blue background.

See also
 NeXTMail
 GNUMail
 Comparison of email clients
 Comparison of feed aggregators

References

External links
 Mail.app 3.0 screen shot of 2007

MacOS email clients
MacOS
IOS software
WatchOS software
Software based on WebKit
IOS
1997 mergers and acquisitions
Mail