One of the biggest challenges to sharing photos and other files via email is that the larger the file(s), the more likely the message will be blocked by a server, somewhere along the way, that places limits on message/attachment size. Because of this, an increasing number of apps and services let you upload a big file to a remote server and then, instead of sending the actual file via email, you send a link to the file; the recipient clicks the link to download the file. (Some Mail plug-ins even automate the process for you.)
This approach works, but it still requires the sender to be tech savvy enough to configure such a workflow. With Yosemite's Mail Drop feature, Apple hopes to make the process seamless. You just add your attachment like you normally would, compose your message, and then send. OS X uploads--automatically and invisibly--larger files to iCloud. If your recipient is using Mail in Yosemite, OS X will download--again, automatically and invisibly--the file and present it in the message just like any other attachment; if the recipient is using another email client, another platform, or an earlier version of OS X, the message will contain a link for downloading the file. Apple says Mail Drop will work with files (or even folders of files) up to 5GB in size, and that files are encrypted in transit for security.
Over the past couple years, Macworld editors have had so many problems with Messages for OS X--and the underlying iMessage service--that many of us have shifted to using AIM on third-party clients. But based on the improvements Apple talked about during the keynote, some of us just may switch back.
For starters, group messaging has finally gotten some attention. While in a group-messaging discussion, you'll be able to easily add and remove participants, to change the thread name ("Vacation Planning") for easier identification on all your devices, and to leave a thread. And each member in the conversation can share his or her location, a la Find My Friends, which should be great for families and friends traveling together--or, say, editors at a tech publication covering a big conference.
For those times when your friend(s) get a bit too chatty, you'll be able to toggle Do Not Disturb for a specific thread, instead of having to enable it for your entire device. Yosemite will also make it easy to view all media in a thread, sans messages.
And a new feature called Soundbites should be a hit, as it lets you quickly record and send audio clips as part of Messages conversations--perfect for those times when it would be easier to just speak a message. (Even better, when you're on your iPhone, you'll be able to listen to received audio, and record and send your own audio clips, from the lock screen by simply moving your iPhone: Lift it to your ear to record, lower the phone to send.)
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