In general, Microsoft says that changing IMAP email settings is fine, however, we have seen some cases when changing/updating email settings generate a loss of data (contact, calendar, notes).
You should avoid changing IMAP email settings or removing the email account from Outlook. Instead, a new Outlook profile should be created.
Note: When removing the email account from the Outlook Profile, the OST file is removed. The OST file stores emails, contacts, calendars, and notes.
When you use Microsoft Outlook, a profile is created and its corresponding OST files. POP accounts, store their information in Outlook Data Files (.pst files).
In Outlook 2013 and earlier versions, IMAP accounts also used an Outlook Data File (.pst). In Outlook 2016 and Outlook for Microsoft 365, IMAP accounts use Offline Outlook Data Files (.ost).
When a new Outlook profile is created, you can always switch to the old profile and backup/restore any missing data.
Click here to learn how to create a new Outlook profile.
How to create a new Outlook profile
In Windows, go to Control Panel | Mail | Show Profiles.
Note: Profiles can also be created within Outlook (File > Account Settings > Manage Profiles).
The Mail Setup dialogue will open. Click on Show Profiles.
The profile(s) currently set up will be listed. Click Add to add a new profile.
Enter a name for your new profile.
You can then setup a mailbox or more for the new profile.
Once it has confirmed that it has connected, you can now click Finish, which will take you back to the Mail dialogue.
As explained before, the client can always switch to the old profile and recover/export any data (email, contact, or calendar) to a pst file. Click here to learn how to do that.
How to export email data
Select File > Open & Export > Import/Export in Outlook.
Select Export to a file, and then select Next.
Select Outlook Data File (.pst), and select Next.
Select the mail folder you want to back up and select Next.
Choose a location and name for your backup file, and then select Finish.
If you want to ensure no one has access to your files, enter and confirm a password, and then select OK.
Note: Please avoid removing the email account if you’re using POP to fetch your emails. Removing the account will remove all your emails.