I'm sorry to hear you're having the same problem. Bell Support seems to want nothing to do with the issue. It's an "application problem". Even though in my case I had 3 different devices, running 3 different mail apps, on 3 different OS and only one...
I too have been experiencing strange behaviour with Bell emails.I have access to my Bell (sympatico) account from 4 different devicesa) a laptop running Windows LiveMail , my main sourceb) a new iPhone 13 running the Outlook appc) an old Samsung ...