When I read an email on Outlook on my computer it still shows as unread on my iPhone. Why is this? Until several months ago it showed it as read.
Either your Outlook email client or your iPhone's email app or both must be set up as a POP3 account and not an IMAP account.
You would need to check in the settings to see what they are set up as.
You should also check that you have the correct settings.
Are both still able to send and receive emails?
What happens when you send and receive when you sign into your email account using a web browser (webmail)?
I don’t think it is a BTInternet server issue since when using BT website to read emails the same emails on my iPhone change to being read. To me this suggests an Outlook problem.
Are you also using the user name T6NYY or is it another user replying to you?
Is your Outlook sending and receiving emails?
Have you checked to see if it is set up as an IMAP or POP3 account?
Just to clarify, when you answered "Yes" was that to you using two user names?
I have assumed that your Outlook can send and receive emails and you are using the word sync to mean replicate what is on the BT servers.
If your Outlook is/has been set up as a POP3 account it can not have synced with the BT servers when you sent an email or read an email. POP3 does not allow that to happen.
IMAP does sync withe servers ie. what you do or set up the server will be replicated on the IMAP device and visa versa.
I've had the same issues ever since BT Yahoo migrated and became BT Mail. And my server settings are IMAP. If I delete an email in Outlook-it does not delete in my BT web based mail or Mail App on my iPhone. But if I delete an email in my web-based mail it does delete on iPhone too.
Are BT ever going to resolve this problem? I've now had my complaint/problem elevated to level 2 but after 3 days I'm still waiting for someone to call me. I can access my emails and associated folders on the BT Mail website but it's not as user friendly as Outlook. Apart from which I'm paying for a service which I'm not getting.