I have an Apple iPhone 6s and use the Mail App on my phone. I am a BT customer and have a BT email address (IMAP).
As of yesterday, when I delete an email from my inbox on my Mail App on my phone and then go into the 'Trash' folder, the email simply disappears wthout me actually deleting it !
So, I logged into my desktop PC on my BT email account and noticed in my 'Trash' folder that the email was still sitting in there, but not in my Mail App on my phone !
(I have done a soft reset on my phone and deleted and re-added my email on my phone, but it still occurs).
Do your Tech colleagues at BT know of any known issues with the current iOS Mail version as to why this is happening, is it something that has occured behind the scenes?