The migration from Lotus Notes to Outlook is never as straightforward as it seems, despite the availability of various free options. The main issue lies in the fact that Outlook is not able to read the native NSF files. As such, there is always the need for an additional conversion step.

The limitations of the free Lotus Notes to Outlook converters are:

CSV Export – only message body is exported – attachments, formatting, calendar and contacts are not included.

IMAP Synchronization – mails are transferred in desired folder structure, but with the limitation of 1GB of NSF file size and 15 mailboxes per conversion process.

Drag and Drop – only suitable for copying of several emails, not whole mailboxes.

Notes users are advised to take extra care while migrating mailboxes because:

The user addresses in Notes are stored in canonical form (CN=John Doe/O=Company), which means that emails sent directly to Notes mailboxes will bounce back if the conversion attempts to change the address to SMTP format (john.doe@company.com).

The names.nsf Address Book is a separate database, which means that any contact lists stored there will be inaccessible in the converted mailbox.

NSFs that are encrypted cannot be converted before being decrypted.

If your Lotus Notes mailboxes contain calendar entries and contact lists, you will need to convert them with a reliable Lotus Notes to Outlook Converter. Kernel Lotus Notes to Outlook Converter can convert Lotus Notes emails, contacts, calendar entries, tasks and more into Outlook PST or Live Exchange format. It supports conversion of local Lotus Notes databases, Domino server and SmartCloud Notes mailboxes into PST and Live Exchange with full folder hierarchy and migration logs.

Local or Exchange based Outlook mailboxes?
Source: https://www.nucleustechnologies.com/lotus-notes-to-office365.html