Peter, I hope your "complaint" gets a cogent response from btinternet.
The use of the "+" is called "plus addressing" and is an important and useful feature of IMAP (Internet message access protocol).? When an IMAP mail server receives a message addressed to user+label@domain the message is automatically placed in a sub-folder named label rather than going directly into the user's inbox.? Even Gmail observes this feature.
Groups.io's use of plus addressing seems analogous to me and makes perfect sense.? I'd hate to see it changed to accommodate a non-compliant ISP.
