They do it on purpose. Gmail allows adding dots between any two letter in the local side of the address, so I'll add them in different locations, for each account I have to make with an organization that prohibits the plus aliases.
I ended up calling customer support and they added it on their end.
At least they did it this time. One time I went to get an oil change at Valvoline. They asked for my email and I reluctantly gave a +valvoline email address and the manager straight up would not type that into the computer. Dude thought I was up to some major shenanigans.
