Software

HI

You can using domino fixup tools , in the domino administrator console do the following
1-l fixup mail\database name.nsf - option (you can find options in domino help)
2-l compact mail\database name.nsf -C

If doesn't help, look here: https://social.technet.microsoft.com/Forums/en-US/ff4b816d-c850-43eb-8f87-15b16909562e/how-to-repair-corrupted-nsf-file-in-lotus-notes?forum=officesetupdeploylegacy

Or:

NSF Repair Kit

NSF Repair Kit is an end-to-end solution for the problem of corrupted Lotus Notes files of the NSF format. This Lotus Notes NSF repair tool uses a uniquely efficient proprietary file analysis core and a number of advanced algorithms to open files with any degree of damage and successfully extract their contents.

For more information: http://www.nsf.repair/nsf