If you are receiving this error

The system cannot find the file specified:

Mapi 0x2, (2)
Function: MAPIInitialize

Context: Arup::DmLib::OasysMapi::CPostOffice::Initialise.

The most likely cause of this is if there are multiple versions of Office/Outlook installed on the PC, or even if a previous Office version was installed the past some aspect of it has been left behind. 

To fix this, right click on the Windows start icon and select Install Apps, or if you are an older version of Windows, Settings or click Start and go to Settings, and browse to Apps > Installed Apps. Search here for Office, Outlook, 365 (as sometimes it's called Microsoft 365), and you may see results like this, showing potentially 3 different Office copies installed.

We need to uninstall the Office/Outlook instances that are not being used here to leave just one.

Just to add that the one that needs to be left on here is the one that is downloading from the Microsoft Office website. The pre-installed Office that can be installed with Windows is not supported. If unsure, download the one installer from the Office 365 website for your login and then uninstall all the other version to install just that one.

After doing this it may need repairing but even the Office full repair may not be enough to fix this full to work with Mail Manager so SaRA from Microsoft should be used here to repair things as this does this at a deeper level: Download Microsoft Support and Recovery Assistant from Official Microsoft Download Center