Finished my conversion today. It was not as painless as I thought it was going to be. The messages still on my mail server did not need manual copying or conversion, but my email database archives did. On my Mac, I stored my emails with MailSteward which exports to several formats including mbox, sql, and tab or comma delimited text files. The mbox export from MailSteward did not export the files from the attachments, so I could not do a straight dump into mbox and and import into Postbox or Thunderbird on the PC. I ended up creating a database and importing the emails into it on Windows from tab delimited text files. The attachments will have to be manually decoded, but I saved all the important ones in other folders as they originally came in, so that is not really much of a problem for me.
On Windows, I had no trouble importing an mbox file into Postbox and Thunderbird that was created from an Apple Mail export to mbox. The messages and attachments were imported without incident in my test.
I tried to find a way to import anything into Windows Mail, but could not find a way to do anything other than setup a POP, IMAP, or Exchange account. It is a super basic program, but it probably satisfies most users, who are doing basic email tasks with a popular email provider.
I looked at Outlook, and I was disappointed that they didn't find a way to put the kitchen sink in there, as they obviously shoehorned in everything else - well, everything but support for generic CalDav and CardDav servers. The irony is not lost on me that I had to return my CalDav and CardDav servers to iCloud to be able switch to Windows. The account import for Calendars, People, and Mail will sync with Apple's and Googles CalDav and CardDav servers, but not directly with others. I know that you can use the Apple CalDav setup and manually input the other server, but I would rather not risk corrupting my calendars and contacts. I do not believe that Outlook can import mbox files without conversion to pst. There are a ton of utilities that claim to do that without data loss.
Unless you hide the ribbon, Outlook's UI is too cluttered. I could never see myself using it and still being able to focus on emails. I know you can hide the ribbon, but for email, you should be able to design a minimal but functional and attractive UI. I think Postbox has hit a good balance there.
For my archived email, I prefer a separate database where I can run more complex queries than search in an email program allows. Now I just have to figure out how to manually export new emails to my database. I may end up going with an email archiving program, or I could probably get one of the Postbox or Thunderbird import/export add-ons to accomplish selective exports.
On a hardware note, my HP EliteDesk 800 mini G3 is really responsive for everything I've thrown at it so far. My email dumps were around 6GB and the import using a USB C flash drive was a few seconds. The first time, I thought it did not copy but was leaving the file on the flash drive, but it had copied all of it over. On a down note, it came out today that HP either purposely or sloppily put a keylogger on the system as part of their media key control program. Less than I week back to PCs after 15 years away, and I am starting to remember why I left in the first place. I am hoping that the slack or corrupt software practices aren't as bad with Microsoft's hardware, but their slow rolling of CalDav and CardDav support is ridiculous.
Good luck with your email transfer.
