I have a user who would like to make a local archive of his Lotus Notes mail file (we use Lotus Notes where I work) and then open it in another mail client, such as Outlook or Thunderbird.
IMAP is a last resort since that requires switching mail servers (which for us involves other prep to reduce the mail file size), but it is not out of the question (that is the suggestion here: How to export mails from Lotus Notes into another mail client?). To clarify, we have IMAP disabled on most of our mail servers (for information security or stability reasons, I'm assuming, though I would need to check the exact reasons with our mail admins), and so if someone wants to use IMAP we move them to the one server reserved for that. However, since we've had stability issues transferring large mail files (I'm talking of 15GB mail files with tens of thousands of emails), we require that people reduce the mail file to under 2GB and the inbox to 1,000 messages. In this particular case the user was wondering if there was some other way to archive his file for later use on other clients, without having to clean up his mail file.
Ideally, I would take the mail replica which is in .nsf format, and convert it to .pst format or some other format. The forums I have found seem to all have posts by people plugging their own dubious converters, so I am wondering if anyone has had any success with a particular converter (if they even exist). Others say it can't really be done easily.
It would also be possible for my customer to keep a copy of Lotus Notes installed solely for opening his mail file, but it would be easier to keep it in another mail client. There is a similar question asked here, but the answers point back to using an IBM product (https://stackoverflow.com/questions/1927655/how-to-read-lotus-notes-mail-archives-nsf).
There are paid converters, such as Stellar NSF to PST Converter, but I'm not sure if they are any good, and this isn't really something worth paying for since the archive would only be needed occasionally and there are other free workarounds (although, as mentioned, not ideal)