I also have problems with emails disappearing without me deleting them. The ones that disappear seem to be random and not necessarily the oldest ones. I have two e-mail clients on my laptop - Windows Mail and eM Client. The problem seemed to start when I stopped using Windows Live Mail and starting using Windows 10 Mail. The account on my laptop is IMAP but on my mobile phone it's POP3. Could the POP3 on my phone be causing the problem but I have been using that for long before this problem started. I have logged onto the TalkTalk Webmail but the same e-mails are there that are on my laptop so I don't think it's because they've been downloaded but then automatically deleted from the TalkTalk Server. Any help would be gratefully received as it's driving me mad!
Webmail operates as an IMAP email account. The emails are on the Mail server in your Mailbox and seen via an Internet browser. An email client or email app set up as an IMAP account views your Mailbox in exactly the same way.
You can delete or move an email using either webmail or any connected IMAP client and that will delete or move the email with each IMAP device mirroring that deletion or move for all folders that are synchronised. Any device can delete any email and that email will be moved to Trash.
Windows 10 Mail will auto-detect the mail server and although it will set the incoming server host name up as imap.talktalk.net instead of mail.talktalk.net the servers will accept either host name. The important bit is that the port is 993 (or mail.talktalk.net:993:1).
A POP3 client will by default download emails to the device that client is running on. There is an option to download and never delete from the server or to delete after say 14 days or 30 days etc.The POP3 client is unlikely to be responsible for random deletions. It could download and delete the entire Mailbox.
Are you sometimes using TalkTalk Webmail and missing that there is an auto-selection of email to force the email view window. It is possible to miss that auto-selection. If you then select additional emails and delete those then the auto-selected email could be included. Deleted emails always are moved to Trash. Of course if you empty the Trash then emails will be totally deleted.
If you don't normally use Webmail then the selection of an email automatically for viewing isn't the issue. I only mentioned that because some users haven't had time to be totally familiar with how the new TalkTalk Mail works and the fact an email is auto-selected has been catching them out.
You'll have been using Windows Live Mail as a POP3 email client. As such it only had the fetch all emails option downloading all emails to the laptop. If you wish to have Windows Mail replicate that action then it just needs setting up as a POP3 account instead of an IMAP account.
Windows Mail > Settings (cog icon) > Manage Accounts > Add Account > Advanced Setup > Internet Email > Account Type - POP3 and populate the other fields as normal.
Have you identified which emails are missing? Are they downloaded to the mobile device?
I appreciated that you're no longer using WLM. I just mentioned that you were using it as a POP3 account and downloading emails to the laptop.
Windows 10 Mail would normally set up as an IMAP account so I gave you the setup sequence to set up a POP3 account in Windows 10 Mail (Windows Mail).
emClient supports either POP3 or IMAP so, as with Windows Mail, you have a choice. emClient includes a good description in their FAQ of the difference between the two protocols.
The TalkTalk server does not delete emails. All emails remain until the user deletes them and then they're moved to Trash. The only user setting is to permanently remove deleted email messages i.e. always empty Trash. (TalkTalk Webmail > Menu > Mail (or Email) > Common)
If all your devices are now set up as IMAP clients then the only deletion will happen when you select an email or group of emails and delete those unwanted emails on any IMAP device or in Webmail. Deleted emails will move to Trash.
Keep an eye on the Mail quota given in Webmail at the bottom of the Folder view (Folder tree). You're allowed 10GB Mailbox size.
Two options with the 'phone.