Mac OS Social Networking
LiSA, the Liquid Information Speaking Assistant for Apple Mail speaks with a real human voice when emails arrive, telling you who they are from. For example:
"You have a message from a friend” "You have a reply from your brother”.
To Use LiSA:
Assign relationships with your contacts such as 'brother', 'boss', 'lover' and so on. When email arrives LiSA will then say: "You have a message from your brother". LiSA understands replies so can also say: "You have a reply from your boss".
LiSA can announce all incoming messages or only those where you have assigned relationships - it's your choice. LiSA can announce the time, on the hour as well.
NOTE: LiSA only works with iCloud mail if you enable two factor authentication.
LiSA REQUIRES that you use Apple Address Book (where she gets your contacts) and Apple Mail.
This is how LiSA works:
LiSA constantly checks for new messages via Mail and announces incoming messages as-and-when they arrive, but not when Mail is in use by the user (when the user would see the incoming message anyway).
If there is an audible chime or beep:
The audible chime you hear is likely the sound made by Mail.app when it received no unread mails. This sound should disappear if you disable "Play sounds for other mail actions" checkbox in General tab of Preferences of Mail.app.
Please also understand that if you have a large amount of email on the server, it could take LiSA quite a while to catch up.
Updated for High Sierra.