Do you have any devices which access your account, or do you just use webmail?
The security of e-mail storage is never guaranteed on a consumer grade system. It always best to keep local copies as well.
Leaving mail in the inbox, is not best practice, as it can easily be deleted by accident.
Have you checked any of the other folders on webmail, to see if they have been put there?
I use Outlook 2016 as a client configured with MAPI. I thought this was recommended as it keeps email in sync. I have have checked all my folders. I have not accidentally dleted these items. I have been archiving after 6 months so that I do have copies. I was under the impression that BT mail did give security.
Its IMAP that keeps mail in sync, not sure about MAPI.
If you are talking about the residential BT mail service, then I would not rely on it for long term security.
BT Business use Microsoft Office 365, which is much more secure.
If you have local copies, then you may be able to copy them back onto BT mail. I use the Thunderbird e-mail client, and I know it can be done with that. Not sure about Outlook.
When did you setup Outlook, was it recently? Does it tie up with the date that you lost your mail on the server?
Sorry I meant IMAP. Outlook 365 has been set up for nearly one year and my mail has worked fine until a day ago when this chunk of my Inbox emails went missing. I am not ware that you can keep local copies when using IMAP only when I used to use POP3.
I would imagine that Outlook 365 would have an offline synchronisation option, where folder contents are retained when you have no Internet connection. This allows you to reply to e-mails while offline, and they will be sent when you go online.
This is certainly the case for Thunderbird, as local copies are kept by default, unless you deselect them.
Thunderbird has an archive facility which can archive e-mails to a local store on your computer.
I am not familiar with Outlook 365, as its intended for business use, I assume you are not a business user, as you are posting on the BT residential forum.
No I am not a business user. As far as I understand it Outlook365 uses pst files with POP3 and this just downloads email and duplicates emails on a PC. Outlook365 with MAPI use OST files which enable offline work. However as soon as you coonect on line synchronisation occurs so if BT Mail has lost emails the client synchronises accordingly. As IMAP is the automatic default option I expected BT Webmail to be reliable.