All services so far seem to accept dots, but the number of possible dot arrangements can be quite limited, and it is a pain to actually use (figure out next one to use, figure out associated service from dot arrangement, etc).
Gmail won't let you put anything arbitrary with dots. So if you're whatever@gmail.com you can use what.ever@gmail.com but not whatever+somemerchant@gmail.com. Other email system obviously can work however they want.
VectorLock|5 years ago