Easiest way to split the Outlook PST files
If you looking at the easiest way to split the Outlook PST files then use MailsDaddy PST Split Tool. It is a most popular single wizard application, which easily divides the Outlook PST file according to date, folder, size, and email id. The software is compatible with all editions of Windows OS and MS Outlook.
More Info- https://www.mailsdaddy.com/pst-split-tool/
Rude Warner commented
If you are facing trouble to Lotus Notes to Outlook PST conversion then don’t take tension and try the NSF to PST Converter Tool. It is a fully reliable and popular software for converting NSF to PST. The NSF Converter also exports the Lotus Notes NSF data into EML, EMLx, MSG, HTML, MHTML, MBOX, VCF, CSV, ICS, Office 365 & Live Exchange Server. The Demo edition of the software helps to imports the first 25 items from each mailbox into Outlook PST format.
More Info- http://www.nsfto.com/pst/