Do you have Notes in Outlook? If you do, make sure they all have subjects.
See this for more Notes syncing info -> iOS: Syncing Notes
Unable to sync notes with Outlook
If notes are not syncing from Outlook, verify that you do not have any notes with no content or subject in Outlook. These notes can prevent Outlook from syncing as expected; removing them or adding a subject should allow syncing to resume.
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More information read this blog: http://diskdatarecovery.jimdo.com/2013/01/23/migrate-and-access-lotus-notes-nsf-files-in-ms-outlook/
Provides user easy-to-use platform to export all the mailbox items of the Lotus Notes including your emails, attachments, contacts, and allows to save the converted files into PST, EML,Office 365, RTF & HTML etc. formats with interactive and user friendly interface. To know more, visit :- http://www.filesrecoverytools.com/nsf-to-pst-converter.html
The Company is dedicated to providing effective and reasonably priced solution for data recovery and email migration. Its export Lotus Notes to Outlook tool is known for its qualitative conversion of NSF file to PST file format.
NSF to PST Converter which provides easy steps and simple GUI interface for converting Lotus Notes to MS Outlook. This software is comprises with advance techniques that perfectly handle conversion between both email clients.It also has extra facility with this tool that converts NSF file into EML or MSG file. It also supports Lotus Notes 6.0, 6.5, 7.0, 8.0.2, 8.5 and compatible with windows 2000/ 2003/ XP/ Vista/7 and Window 8.
Get more info: http://www.softmagnat.com/nsf-to-pst-converter.html