Why this outlook mail message not able to read subjects using lower versions 2018.2,2.3, 2.4

From where can I download UiPath 2018.2.3?

As I wrote here:

I strongly not recommend to use these version of Studio.

May I know the reason why you recommand not to use this version Studio?

Will this 2018.2.3 version supports Get outlook mail message activity ?

As every update it brings not only new features but also a bug fixes. In case 2018.2.3 and 2018.2.4 there was a huge bug fixed in later version. You can see it in Release Note for newer version. Little quote here:

“A security fix has been made for Orchestrator which prevents an authenticated user to elevate their privileges and execute commands remotely on a target machine.”

" Due to localization updates for our activities, Invoke Code was not working properly and threw an error at runtime."

So, Invoke code threws an errors at runtime. Then how to use invoke code activity in version 2018.2.3. Is there any alternative?

2018.2.3 is better to use or not in future…it may be of community or enterprise edition.

You can just simply update your Studio to newer version.