If you were using Port 143, that is an insecure port so it may be that the BTMail team are targeting users of that port to get them to change. Hopefully the moderators will be able to find out from the email team.
Thank you. I shall wait and see.
Could well be.
I still can't see how changing the port resulted in the loss of folders though.
In any event, changing the port would/should not have changed your folders and contents.
Are you sure the missing folders/emails are still on the BT servers on webmail?
I agree, and yes the folders and all of their contents are still on the BT servers on webmail.
Unbelievable.
I shut my machine down after first setting the advanced server settings to completely blank.
I then restarted and relaunched Apple Mail. and lo and behold it started downloading all of my missing mails into their relevant folders.
Who knows what caused this malfunction, but I am glad that it appears to be sorted.
Thanks for your suggestions and help.
Hi there, @EricC
I've double checked this with our email team, and they've confirmed that this is definitely a genuine email, and is aimed at ensuring customers are using secure ports with their client.
They've recommended restarting your machine and mail client, as the settings you have described are definitely correct and have been tested with a similar configuration at our end.
Peter
Glad to hear all is working again.
Cheers