Dear Elizabeth Fowler1
Thank you for posting in the Microsoft community.
I have read your question carefully and understand your dilemma in switching between NEW OUTLOOK and OUTLOOK Classic applications.
In my personal experience, the biggest problem I've encountered is that files don't back up perfectly after switching to NEW OUTLOOK, and it doesn't export emails to be backed up individually like it does with OUTLOOK Classic. And as you said, there are all sorts of small problems with connecting to mailboxes and usage habits.
I thought about it and decided to switch back to the old Outlook app, but then I realized that the emails from the last few weeks were not updated in time in the old Outlook app.
As a technician I thought carefully about the difference in design logic between the two.
NEW Outlook is more suitable for hotmail or outlook mailboxes with exchange protocol. It is synchronized with the server in both directions and there is almost no pressure to back up the mail.
Outlook Classic is more suitable for your current use case.
First of all, considering the problem of backing up emails in the future, the export function of Outlook Classic is obviously more suitable for backing up.
Secondly, Outlook Classic is more compatible and less likely to have problems such as not being able to connect to the mail server.
Thirdly, Outlook Classic has more complete counting and editing functions.
I have thought carefully about your current dilemma. Since you have been using New Outlook for some time and have set up many classified folders, I would suggest that you try to distribute these classified mails to a new Outlook.com mailbox and then backup and classify them in this Outlook.com mailbox. After that, make sure the important data has been backed up and you can switch to the old version of OUTLOOK to continue to use it. At this point you can either configure your new OUTLOOK.COM mailbox using a Windows device, export your important folders and import them into the MAC OUTLOOK Classic application, or choose to use the Forward Mail method to transfer important mail to Classic Outlook.
I realize how tedious and difficult these operations can be, but this is the best solution I could come up with after careful consideration of the differences between the NEW OUTLOOK and Classic OUTLOOK applications.
I would also recommend that you continue to contact OUTLOOK online support team to help you further backup your mail, which is probably the most important thing you can do.
In addition, you have been prompted that you need to delete the old version of OUTLOOK to free up space, this prompt is due to the limited disk space on your MAC device. However, if you do delete the old version of OUTLOOK, the mail structure on your old OUTLOOK will be deleted. Therefore, I suggest you to backup your important mail data anyway.
The reason why I communicate with you so much is that I can feel the importance of your mail through your words. Personally, I would suggest you to backup your mails to PST file individually by year, and then clean up the mails in OUTLOOK regularly, because MAC system can not carry too much mail data by itself.
I hope the above information can help you.
Looking forward to your further reply.
Best Regards
Clara G| Microsoft Community Support Specialist