Hi, welcome to the forums.
The timeout "issue" has been happening for a while now, and is apparently a security issue. However it does seem to affect people differently, with some users reporting no timeout. There could be a variety of reasons, maybe tied in with various end user add-ons etc.
There have been many reports over the years where BTinternet has bounced emails destined for end users - due to apparent spam issues. BT want companies to jump through hoops to stop it happening. Though there have been no reports recently, it did happen a few times.
A BT mail expert said that they have recently updated their systems, including antispam, inferring people would see less spam - but it might appear to have backfired in that there is more blocking of proper emails. As an aside to these updates, less is apparently sent to the Spam/Bulk folder, so it's not obvious any spam is arriving - or indeed possible false positives. "Obvious" spam is hard to pick up by machines.
Unfortunately you will not get anyone to listen, in particular the mail expert as they seem to deny any issues.
The best thing to do is start using as different mail service, e.g. Gmail, and begin to change over telling contacts etc.
