Step by Step for IMAP Gmail for now.

Forums:

1) type URL www.Gmail.com
2) Enter your Email address
3) Enter your Password
4) 2-Step verification (Get a verification code from the Google Authenticator app) that if you did it.

5) look for "Your app passwords" and click it.
6) Select app choose "other (custom name)"
7) type "XNotifier" for example.
8) copy "code number" and do not lost... see below *13)*.

9) Open XNotifier Options
10) Account
11) Drag down and choose IMAP
12) Username... type your email __________@gmail.com
13) Password... "code number" paste it from copy *8)* see above.
14) Server... imap.gmail.com
15) Alias... IMAP/Gmail ____your nickname email____
16) Link... file:///Applications/Mail.app/Contents/MacOS/Mail 
(that is for Mac... you need to find path for window)

[X] Notifiy inbox only???
[X] Show folders???
[   ] Open automatically

It work great for time being until Tobwithu update Gmail scripts.
I have not test yet with Yahoo, I will let you know later.

ENJOY
CFBancroft