AFAIK you can't use local PST files with OWA. My understanding is in general webmail of any kind can only work with data which is local to it i.e. the web server serving up the webmail app. Your PST files are not local to M365 web servers. I just asked the question about OWA to get some idea of how closely you're wedded to desktop Outlook.

If you do end up using a cloud back end you can use desktop Outlook to migrate the contents of local PST files to the cloud. You can drag/copy from a PST to a folder or other location in your cloud mailbox.

>Thank you for a detailed reply. I have not tried OWA; maybe I should do it. Although I have several PST (Outlook type) files that I use in my Outlook. I wonder if I would be able to use them from the OWA; or start from scratch.
>
>You are right, however. I am so used to many features of Outlook that it would be super difficult for me to switch to another client.
>
>Perhaps, the first matter of business, is to attempt to resolve the issue I have with M365 on Windows 10 (which started after my attempt - failed though - to fix the user name :()
>
>Again, thank you.
>
>>Client-side: Have you tried Outlook Web App (OWA), and is it "good enough"? If OWA isn't good enough, then you're probably "hooked" on the desktop Outlook experience and would likely find alternatives not good enough, either.
>
>>
>>OTOH maybe an alternative client would be "good enough" but you'd have to learn how to use it, especially if you currently use features of Outlook which you'd want to duplicate (assuming they're present at all). There would also be the question of migrating your existing data to a new client and/or back end.
>>
>>Server-side: if you want to be able to work with mail on more than one device you need hosted mail like Exchange Online or alternatives like Gmail. With hosted mail your choices are basically IMAP or Exchange. In my limited experience IMAP servers are a poor man's Exchange. Clients have called me when they're having sync issues and depending on the exact configuration of the IMAP server it can be too easy to lose data while troubleshooting. Outlook with an Exchange back end is more robust.
>>
>>In some countries/jurisdictions there are regulations about data storage e.g. Canada has regulations that "personal" information must be stored while at rest in servers located in Canada. M365 hosts Canadian tenants in data centers in Toronto and Quebec City so it meets that requirement.
>>
>>This may not matter to you if you're a one man operation but the collaboration features of Outlook with an Exchange back end are, to the best of my knowledge, not matched by any other product. It's arguably one of Microsoft's "crown jewels".
>>
>>Admittedly I work only with M365 business tenancies but I've found support to be excellent, accessed from the admin center at https://portal.office.com .
>>
>>M365 has had a couple of spectacular worldwide outages fairly recently, and that's always a worry with a cloud solution. That would take down send/receive and webmail, but if you're using an Outlook desktop client you could still work with locally cached content until service is restored.
>>
>>>Hi,
>>>
>>>I am getting sick and tired of issues and non-existing support from MS$ with MS 365. I don't mind paying about $100 a year if it worked. But when I have a problem I have no support.
>>>
>>>So, I am investigating alternatives. To run on Windows 10 PC. I found the following, online:
>>>Zoho Office
>>>G Suite (Google)
>>>WPS Office
>>>
>>>For me, the most important is to have email client (currently using Outlook).
>>>
>>>Any suggestions?
>>>
>>>TIA