Hi,
It happened once before on the AIM service.
They stopped allowing pictures to be sent In-Line (displayed) when there were a spate of issues with files that looked like .jpegs but contained malicious code.
There was one that could even infect a Mac and then the Bonjour linked computer using iChat.
https://en.wikipedia.org/wiki/Leap_%28computer_worm%29
You got sent the malicious jpeg and when opened (or attempted it install a worm) this then used th iChat Bonjour account to infect other computers.
This trend seemed to go away and I am sure AIM also did things to try and prevent it and In-line Pics were allowed again.
We seem to have got to a similar place again but not just with .jpegs but all picture formats.
Apple also seems to have added the Auto-zippping of Folders.
The whole process is designed to make you think and check at each stage but what tends to happen is that people are waiting for something and click and double click things too fast to think if there is a risk so it more of a hindrance than a benefit.
Because the same subroutine is used for Jabber accounts as well as the AIM one when doing this it effects Jabber chats as well.
I am not sure that it will work again like it does in iMessages conversations (and like it did before)
8:48 pm Monday; November 30, 2015
iMac 2.5Ghz i5 2011 (Mavericks 10.9)
G4/1GhzDual MDD (Leopard 10.5.8)
MacBookPro 2Gb (Snow Leopard 10.6.8)
Mac OS X (10.6.8),
Couple of iPhones and an iPad
