I suddenly found my emails composed on my phone weren't being sent. I tried removing and re adding my BT account from apple mail but no luck, it complained that the SMTP server password was wrong which was a complete red herring as I can login with the password to my webmail. On top of this if I disconnect my phone from my wifi and use 5G then the email sends.
I then searched this forum and found this is a very common problem and it is definitely down to issues with one or more BY SMTP servers. BT please get this fixed ASAP as it is a right royal PITA and I am paying for premium email service.
