Missing flagged emails

[#1]

Hi

Don't know if anyone can help me?

I have had repeated emails from plusnet about the size of my mailbox, this was due to switching to imap I believe and not realising that emails were not being removed from the server (having previously always used pop).  I struggled to delete emails so eventually I have switched back to pop on my PC (using windows 10 and outlook) and imap (I think) on my phone.

I have cleared everything off the server, however, I now seem to have lost some emails which were in my inbox on my PC and which had been flagged.  These include things like purchase receipts, emailed insurance documents, holiday booking details (which I am going to need in order to cancel and claim a refund).  I don't understand where these have gone.  They're not on the server and not in my inbox or any archives.  I have searched in my online inbox and folders (folders are empty) and in my outlook inbox and archive folders, and also searched for archive folders on the hard drive of my PC, can't find anything in between November 2019 and today, I don't know if this is linked to when I switched back to pop from imap.

Any idea where these emails could have gone or if there is any chance of retrieving them as I really need them back?

I don't understand how any of this works, so please keep explanations low-tech!

Thanks in advance!

[#2]

"I don't understand how any of this works, so please keep explanations low-tech!"

Oh dear … in which case, swapping from IMAP to POP3 was a bit rash!  It would have been better for you to simply archive old emails to local storage folders, but sadly such advice does not help now.

Which version of Outlook are you using?  There are a number of email programs which go under the moniker of "Outlook" some a good, other are near useless (Win10 'mail' is branded Outlook too).

Generally under Outlook, each IMAP account has separate folder structures, one for each account.  With POP3 all emails are often collected into the same folder set and found at the top of the left pane under "Outlook Data File".  Are the "missing" emails to be found in there?

Given you are accessing the mailbox from more than one device, you would be far better off using IMAP on everything which ensures that all devices have the same view of all emails, including those sent from different devices.  Note that with POP3 sent items are only to be found on the sending device.