You are correct @landie57 , there was an incident earlier this year when the spam filters weren't working correctly and everyone was being swamped with spam for a few days before BT fixed it and an apology was posted on this forum.
At the moment, I am getting increasingly more spam emails each day despite me marking each and every one as spam, most of which have the same characteristics along the lines of those already reported by myself and other posters.
I have set up some rules of my own whereby anything coming from a gmail address other than those I know get redirected in to a 'filtered' email folder. From there, I get the opportunity to review them and either move them to my inbox if they are genuine (very rare) or report them as spam (virtually all of them).
I have similar rules set up to redirect emails referring to bitcoin or other less savoury subjects to the same 'filtered' email folder for me to review at my leisure, but I still find some getting through to my inbox before I find myself having to set up yet another rule of my own.
Just come on here to see if anyone else is experiencing higher levels of spam, and I see that is the case.
They don't look particularly sophisticated and they come in waves.
I mark as spam and block domain but don't know what good it does.
Does anyone know if simply opening the emails sends anything back to the sender? If so how do I prevent that.
I'm not clicking on any links in case anyone asks.
Images in email are commonly used by spammers to determine whether or not you've opened an email. This implicitly also tells them whether the email was delivered successfully and whether the destination email address was valid with a "live" person opening it.
You can turn off loading Images in BTMail by logging onto your email account and going to the settings by clicking on your username at the top right.
Then go to "Mail" > "Block Images" and select an option that suits your needs. Then click "Save"